MirOS Manual: false(1), mksh(1), pwd(1), sh(1), sleep(1), test(1), true(1), [(1)

MKSH(1)                      BSD Reference Manual                      MKSH(1)

NAME

     mksh, sh - MirBSD Korn shell

SYNOPSIS

     mksh [-+abCefhiklmnprUuvXx] [-T [!]tty | -] [-+o option] [-c string | -s
          | file [argument ...]]
     builtin-name [argument ...]

DESCRIPTION

     mksh is a command interpreter intended for both interactive and shell
     script use. Its command language is a superset of the sh(C) shell
     language and largely compatible to the original Korn shell.

I'm an Android user, so what's mksh?

     mksh is a UNIX shell / command interpreter, similar to COMMAND.COM or
     CMD.EXE, which has been included with Android Open Source Project for a
     while now. Basically, it's a program that runs in a terminal (console
     window), takes user input and runs commands or scripts, which it can also
     be asked to do by other programs, even in the background. Any privilege
     pop-ups you might be encountering are thus not mksh issues but questions
     by some other program utilising it.

Invocation

     Most builtins can be called directly, for example if a link points from
     its name to the shell; not all make sense, have been tested or work at
     all though.

     The options are as follows:

     -c string  mksh will execute the command(s) contained in string.

     -i         Interactive shell. A shell is "interactive" if this option is
                used or if both standard input and standard error are attached
                to a tty(4). An interactive shell has job control enabled, ig-
                nores the SIGINT, SIGQUIT, and SIGTERM signals, and prints
                prompts before reading input (see the PS1 and PS2 parameters).
                It also processes the ENV parameter or the mkshrc file (see
                below). For non-interactive shells, the trackall option is on
                by default (see the set command below).

     -l         Login shell. If the basename the shell is called with (i.e.
                argv[0]) starts with '-' or if this option is used, the shell
                is assumed to be a login shell; see Startup files below.

     -p         Privileged shell. A shell is "privileged" if the real user ID
                or group ID does not match the effective user ID or group ID
                (see getuid(2) and getgid(2)). Clearing the privileged option
                causes the shell to set its effective user ID (group ID) to
                its real user ID (group ID). For further implications, see
                Startup files. If the shell is privileged and this flag is not
                explicitly set, the "privileged" option is cleared automati-
                cally after processing the startup files.

     -r         Restricted shell. A shell is "restricted" if this option is
                used. The following restrictions come into effect after the
                shell processes any profile and ENV files:

                •   The cd (and chdir) command is disabled.
                •   The SHELL, ENV, and PATH parameters cannot be changed.
                •   Command names can't be specified with absolute or relative
                    paths.
                •   The -p option of the built-in command command can't be
                    used.
                •   Redirections that create files can't be used (i.e. '>',
                    '>|', '>>', '<>').

     -s         The shell reads commands from standard input; all non-option
                arguments are positional parameters.

     -T name    Spawn mksh on the tty(4) device given. The paths name,
                /dev/ttyCname and /dev/ttyname are attempted in order. Unless
                name begins with an exclamation mark ('!'), this is done in a
                subshell and returns immediately. If name is a dash ('-'), de-
                tach from controlling terminal (daemonise) instead.

     In addition to the above, the options described in the set built-in com-
     mand can also be used on the command line: both [-+abCefhkmnuvXx] and
     [-+o option] can be used for single letter or long options, respectively.

     If neither the -c nor the -s option is specified, the first non-option
     argument specifies the name of a file the shell reads commands from. If
     there are no non-option arguments, the shell reads commands from the
     standard input. The name of the shell (i.e. the contents of $0) is deter-
     mined as follows: if the -c option is used and there is a non-option ar-
     gument, it is used as the name; if commands are being read from a file,
     the file is used as the name; otherwise, the basename the shell was
     called with (i.e. argv[0]) is used.

     The exit status of the shell is 127 if the command file specified on the
     command line could not be opened, or non-zero if a fatal syntax error oc-
     curred during the execution of a script. In the absence of fatal errors,
     the exit status is that of the last command executed, or zero, if no com-
     mand is executed.

Startup files

     For the actual location of these files, see FILES. A login shell
     processes the system profile first. A privileged shell then processes the
     suid profile. A non-privileged login shell processes the user profile
     next. A non-privileged interactive shell checks the value of the ENV
     parameter after subjecting it to parameter, command, arithmetic and tilde
     ('~') substitution; if unset or empty, the user mkshrc profile is pro-
     cessed; otherwise, if a file whose name is the substitution result ex-
     ists, it is processed; non-existence is silently ignored. A privileged
     shell then drops privileges if neither was the -p option given on the
     command line nor set during execution of the startup files.

Command syntax

     The shell begins parsing its input by removing any backslash-newline com-
     binations, then breaking it into words. Words (which are sequences of
     characters) are delimited by unquoted whitespace characters (space, tab,
     and newline) or meta-characters ('<', '>', '|', ';', '(', ')', and '&').
     Aside from delimiting words, spaces and tabs are ignored, while newlines
     usually delimit commands. The meta-characters are used in building the
     following tokens: '<', '<&', '<<', '<<<', '>', '>&', '>>', '&>', etc. are
     used to specify redirections (see Input/output redirection below); '|' is
     used to create pipelines; '|&' is used to create co-processes (see Co-
     processes below); ';' is used to separate commands; '&' is used to create
     asynchronous pipelines; '&&' and '||' are used to specify conditional ex-
     ecution; ';;', ';&' and ';|' are used in case statements; '(( .. ))' is
     used in arithmetic expressions; and lastly, '( .. )' is used to create
     subshells.

     Whitespace and meta-characters can be quoted individually using a
     backslash ('\'), or in groups using double ('"') or single (''') quotes.
     Note that the following characters are also treated specially by the
     shell and must be quoted if they are to represent themselves: '\', '"',
     ''', '#', '$', '`', '~', '{', '}', '*', '?', and '['. The first three of
     these are the above mentioned quoting characters (see Quoting below);
     '#', if used at the beginning of a word, introduces a comment - every-
     thing after the '#' up to the nearest newline is ignored; '$' is used to
     introduce parameter, command, and arithmetic substitutions (see
     Substitution below); '`' introduces an old-style command substitution
     (see Substitution below); '~' begins a directory expansion (see Tilde
     expansion below); '{' and '}' delimit csh(1)-style alterations (see Brace
     expansion below); and finally, '*', '?', and '[' are used in file name
     generation (see File name patterns below).

     As words and tokens are parsed, the shell builds commands, of which there
     are two basic types: simple-commands, typically programmes that are exe-
     cuted, and compound-commands, such as for and if statements, grouping
     constructs, and function definitions.

     A simple-command consists of some combination of parameter assignments
     (see Parameters below), input/output redirections (see Input/output
     redirections below), and command words; the only restriction is that
     parameter assignments come before any command words. The command words,
     if any, define the command that is to be executed and its arguments. The
     command may be a shell built-in command, a function, or an external com-
     mand (i.e. a separate executable file that is located using the PATH
     parameter; see Command execution below). Note that all command constructs
     have an exit status: for external commands, this is related to the status
     returned by wait(2) (if the command could not be found, the exit status
     is 127; if it could not be executed, the exit status is 126); the exit
     status of other command constructs (built-in commands, functions,
     compound-commands, pipelines, lists, etc.) are all well-defined and are
     described where the construct is described. The exit status of a command
     consisting only of parameter assignments is that of the last command sub-
     stitution performed during the parameter assignment or 0 if there were no
     command substitutions.

     Commands can be chained together using the '|' token to form pipelines,
     in which the standard output of each command but the last is piped (see
     pipe(2)) to the standard input of the following command. The exit status
     of a pipeline is that of its last command, unless the pipefail option is
     set (see there). All commands of a pipeline are executed in separate sub-
     shells; this is allowed by POSIX but differs from both variants of AT&T
     UNIX ksh, where all but the last command were executed in subshells; see
     the read builtin's description for implications and workarounds. A pipe-
     line may be prefixed by the '!' reserved word which causes the exit
     status of the pipeline to be logically complemented: if the original
     status was 0, the complemented status will be 1; if the original status
     was not 0, the complemented status will be 0.

     Lists of commands can be created by separating pipelines by any of the
     following tokens: '&&', '||', '&', '|&', and ';'. The first two are for
     conditional execution: "cmd1 && cmd2" executes cmd2 only if the exit
     status of cmd1 is zero; '||' is the opposite - cmd2 is executed only if
     the exit status of cmd1 is non-zero. '&&' and '||' have equal precedence
     which is higher than that of '&', '|&', and ';', which also have equal
     precedence. Note that the '&&' and '||' operators are "left-associative".
     For example, both of these commands will print only "bar":

           $ false && echo foo || echo bar
           $ true || echo foo && echo bar

     The '&' token causes the preceding command to be executed asynchronously;
     that is, the shell starts the command but does not wait for it to com-
     plete (the shell does keep track of the status of asynchronous commands;
     see Job control below). When an asynchronous command is started when job
     control is disabled (i.e. in most scripts), the command is started with
     signals SIGINT and SIGQUIT ignored and with input redirected from
     /dev/null (however, redirections specified in the asynchronous command
     have precedence). The '|&' operator starts a co-process which is a spe-
     cial kind of asynchronous process (see Co-processes below). Note that a
     command must follow the '&&' and '||' operators, while it need not follow
     '&', '|&', or ';'. The exit status of a list is that of the last command
     executed, with the exception of asynchronous lists, for which the exit
     status is 0.

     Compound commands are created using the following reserved words. These
     words are only recognised if they are unquoted and if they are used as
     the first word of a command (i.e. they can't be preceded by parameter as-
     signments or redirections):

           case     else     function     then      !       (
           do       esac     if           time      [[      ((
           done     fi       in           until     {
           elif     for      select       while     }

     In the following compound command descriptions, command lists (denoted as
     list) that are followed by reserved words must end with a semicolon, a
     newline, or a (syntactically correct) reserved word. For example, the
     following are all valid:

           $ { echo foo; echo bar; }
           $ { echo foo; echo bar<newline>}
           $ { { echo foo; echo bar; } }

     This is not valid:

           $ { echo foo; echo bar }

     (list)
           Execute list in a subshell. There is no implicit way to pass en-
           vironment changes from a subshell back to its parent.

     { list; }
           Compound construct; list is executed, but not in a subshell. Note
           that '{' and '}' are reserved words, not meta-characters.

     case word in [[(] pattern [| pat] ...) list [;; | ;& | ;| ]]  ... esac
           The case statement attempts to match word against a specified
           pattern; the list associated with the first successfully matched
           pattern is executed. Patterns used in case statements are the same
           as those used for file name patterns except that the restrictions
           regarding '.' and '/' are dropped. Note that any unquoted space be-
           fore and after a pattern is stripped; any space within a pattern
           must be quoted. Both the word and the patterns are subject to
           parameter, command, and arithmetic substitution, as well as tilde
           substitution.

           For historical reasons, open and close braces may be used instead
           of in and esac e.g. case $foo { *) echo bar;; }.

           The list terminators are:

           ';;'  Terminate after the list.

           ';&'  Fall through into the next list.

           ';|'  Evaluate the remaining pattern-list tuples.

           The exit status of a case statement is that of the executed list;
           if no list is executed, the exit status is zero.

     for name [in word ...]; do list; done
           For each word in the specified word list, the parameter name is set
           to the word and list is executed. If in is not used to specify a
           word list, the positional parameters ($1, $2, etc.) are used in-
           stead. For historical reasons, open and close braces may be used
           instead of do and done e.g. for i; { echo $i; }. The exit status of
           a for statement is the last exit status of list; if list is never
           executed, the exit status is zero.

     if list; then list; [elif list; then list;] ... [else list;] fi
           If the exit status of the first list is zero, the second list is
           executed; otherwise, the list following the elif, if any, is exe-
           cuted with similar consequences. If all the lists following the if
           and elifs fail (i.e. exit with non-zero status), the list following
           the else is executed. The exit status of an if statement is that of
           non-conditional list that is executed; if no non-conditional list
           is executed, the exit status is zero.

     select name [in word ...]; do list; done
           The select statement provides an automatic method of presenting the
           user with a menu and selecting from it. An enumerated list of the
           specified word(s) is printed on standard error, followed by a
           prompt (PS3: normally '#? '). A number corresponding to one of the
           enumerated words is then read from standard input, name is set to
           the selected word (or unset if the selection is not valid), REPLY
           is set to what was read (leading/trailing space is stripped), and
           list is executed. If a blank line (i.e. zero or more IFS octets) is
           entered, the menu is reprinted without executing list.

           When list completes, the enumerated list is printed if REPLY is
           NULL, the prompt is printed, and so on. This process continues un-
           til an end-of-file is read, an interrupt is received, or a break
           statement is executed inside the loop. If "in word ..." is omitted,
           the positional parameters are used (i.e. $1, $2, etc.). For histor-
           ical reasons, open and close braces may be used instead of do and
           done e.g. select i; { echo $i; }. The exit status of a select
           statement is zero if a break statement is used to exit the loop,
           non-zero otherwise.

     until list; do list; done
           This works like while, except that the body is executed only while
           the exit status of the first list is non-zero.

     while list; do list; done
           A while is a pre-checked loop. Its body is executed as often as the
           exit status of the first list is zero. The exit status of a while
           statement is the last exit status of the list in the body of the
           loop; if the body is not executed, the exit status is zero.

     function name { list; }
           Defines the function name (see Functions below). Note that redirec-
           tions specified after a function definition are performed whenever
           the function is executed, not when the function definition is exe-
           cuted.

     name() command
           Mostly the same as function (see Functions below). Whitespace
           (space or tab) after name will be ignored most of the time.

     function name() { list; }
           The same as name() (bashism). The function keyword is ignored.

     time [-p] [pipeline]
           The Command execution section describes the time reserved word.

     (( expression ))
           The arithmetic expression expression is evaluated; equivalent to
           "let expression" (see Arithmetic expressions and the let command,
           below).

     [[ expression ]]
           Similar to the test and [ ... ] commands (described later), with
           the following exceptions:

           •   Field splitting and file name generation are not performed on
               arguments.

           •   The -a (AND) and -o (OR) operators are replaced with '&&' and
               '||', respectively.

           •   Operators (e.g. '-f', '=', '!') must be unquoted.

           •   Parameter, command, and arithmetic substitutions are performed
               as expressions are evaluated and lazy expression evaluation is
               used for the '&&' and '||' operators. This means that in the
               following statement, $(<foo) is evaluated if and only if the
               file foo exists and is readable:

                     $ [[ -r foo && $(<foo) = b*r ]]

           •   The second operand of the '!=' and '=' expressions are a subset
               of patterns (e.g. the comparison [[ foobar = f*r ]] succeeds).
               This even works indirectly:

                     $ bar=foobar; baz='f*r'
                     $ [[ $bar = $baz ]]; echo $?
                     $ [[ $bar = "$baz" ]]; echo $?

               Perhaps surprisingly, the first comparison succeeds, whereas
               the second doesn't. This does not apply to all extglob meta-
               characters, currently.

Quoting

     Quoting is used to prevent the shell from treating characters or words
     specially. There are three methods of quoting. First, '\' quotes the fol-
     lowing character, unless it is at the end of a line, in which case both
     the '\' and the newline are stripped. Second, a single quote (''') quotes
     everything up to the next single quote (this may span lines). Third, a
     double quote ('"') quotes all characters, except '$', '`' and '\', up to
     the next unquoted double quote. '$' and '`' inside double quotes have
     their usual meaning (i.e. parameter, command, or arithmetic substitution)
     except no field splitting is carried out on the results of double-quoted
     substitutions. If a '\' inside a double-quoted string is followed by '\',
     '$', '`', or '"', it is replaced by the second character; if it is fol-
     lowed by a newline, both the '\' and the newline are stripped; otherwise,
     both the '\' and the character following are unchanged.

     If a single-quoted string is preceded by an unquoted '$', C style
     backslash expansion (see below) is applied (even single quote characters
     inside can be escaped and do not terminate the string then); the expanded
     result is treated as any other single-quoted string. If a double-quoted
     string is preceded by an unquoted '$', the latter is ignored.

Backslash expansion

     In places where backslashes are expanded, certain C and AT&T UNIX ksh or
     GNU bash style escapes are translated. These include '\a', '\b', '\f',
     '\n', '\r', '\t', '\U########', '\u####', and '\v'. For '\U########' and
     '\u####', "#" means a hexadecimal digit, of thich there may be none up to
     four or eight; these escapes translate a Unicode codepoint to UTF-8.
     Furthermore, '\E' and '\e' expand to the escape character.

     In the print builtin mode, '\"', '\'', and '\?' are explicitly excluded;
     octal sequences must have the none up to three octal digits "#" prefixed
     with the digit zero ('\0###'); hexadecimal sequences '\x##' are limited
     to none up to two hexadecimal digits "#"; both octal and hexadecimal se-
     quences convert to raw octets; '\#', where # is none of the above,
     translates to \# (backslashes are retained).

     Backslash expansion in the C style mode slightly differs: octal sequences
     '\###' must have no digit zero prefixing the one up to three octal digits
     "#" and yield raw octets; hexadecimal sequences '\x#*' greedily eat up as
     many hexadecimal digits "#" as they can and terminate with the first
     non-hexadecimal digit; these translate a Unicode codepoint to UTF-8. The
     sequence '\c#', where "#" is any octet, translates to Ctrl-# (which basi-
     cally means, '\c?' becomes DEL, everything else is bitwise ANDed with
     0x1F). Finally, '\#', where # is none of the above, translates to # (has
     the backslash trimmed), even if it is a newline.

Aliases

     There are two types of aliases: normal command aliases and tracked
     aliases. Command aliases are normally used as a short hand for a long or
     often used command. The shell expands command aliases (i.e. substitutes
     the alias name for its value) when it reads the first word of a command.
     An expanded alias is re-processed to check for more aliases. If a command
     alias ends in a space or tab, the following word is also checked for
     alias expansion. The alias expansion process stops when a word that is
     not an alias is found, when a quoted word is found, or when an alias word
     that is currently being expanded is found. Aliases are specifically an
     interactive feature: while they do happen to work in scripts and on the
     command line in some cases, aliases are expanded during lexing, so their
     use must be in a separate command tree from their definition; otherwise,
     the alias will not be found. Noticeably, command lists (separated by
     semicolon, in command substitutions also by newline) may be one same
     parse tree.

     The following command aliases are defined automatically by the shell:

           autoload='typeset -fu'
           functions='typeset -f'
           hash='alias -t'
           history='fc -l'
           integer='typeset -i'
           local='typeset'
           login='exec login'
           nameref='typeset -n'
           nohup='nohup '
           r='fc -e -'
           stop='kill -STOP'
           type='whence -v'

     Tracked aliases allow the shell to remember where it found a particular
     command. The first time the shell does a path search for a command that
     is marked as a tracked alias, it saves the full path of the command. The
     next time the command is executed, the shell checks the saved path to see
     that it is still valid, and if so, avoids repeating the path search.
     Tracked aliases can be listed and created using alias -t. Note that
     changing the PATH parameter clears the saved paths for all tracked
     aliases. If the trackall option is set (i.e. set -o trackall or set -h),
     the shell tracks all commands. This option is set automatically for non-
     interactive shells. For interactive shells, only the following commands
     are automatically tracked: cat(1), cc(1), chmod(1), cp(1), date(1),
     ed(1), emacs(1), grep(1), ls(1), make(1), mv(1), pr(1), rm(1), sed(1),
     sh(1), vi(1), and who(1).

Substitution

     The first step the shell takes in executing a simple-command is to per-
     form substitutions on the words of the command. There are three kinds of
     substitution: parameter, command, and arithmetic. Parameter substitu-
     tions, which are described in detail in the next section, take the form
     $name or ${...}; command substitutions take the form $(command) or
     (deprecated) `command` or (executed in the current environment)
     ${ command;} and strip trailing newlines; and arithmetic substitutions
     take the form $((expression)). Parsing the current-environment command
     substitution requires a space, tab or newline after the opening brace and
     that the closing brace be recognised as a keyword (i.e. is preceded by a
     newline or semicolon). They are also called funsubs (function substitu-
     tions) and behave like functions in that local and return work, and in
     that exit terminates the parent shell.

     Another variant of substitution are the valsubs (value substitutions)
     ${|command;} which are also executed in the current environment, like
     funsubs, but share their I/O with the parent; instead, they evaluate to
     whatever the, initially empty, expression-local variable REPLY is set to
     within the commands.

     If a substitution appears outside of double quotes, the results of the
     substitution are generally subject to word or field splitting according
     to the current value of the IFS parameter. The IFS parameter specifies a
     list of octets which are used to break a string up into several words;
     any octets from the set space, tab, and newline that appear in the IFS
     octets are called "IFS whitespace". Sequences of one or more IFS whi-
     tespace octets, in combination with zero or one non-IFS whitespace oc-
     tets, delimit a field. As a special case, leading and trailing IFS whi-
     tespace and trailing IFS non-whitespace are stripped (i.e. no leading or
     trailing empty field is created by it); leading non-IFS whitespace does
     create an empty field.

     Example: If IFS is set to "<space>:", and VAR is set to
     "<space>A<space>:<space><space>B::D", the substitution for $VAR results
     in four fields: 'A', 'B', '' (an empty field), and 'D'. Note that if the
     IFS parameter is set to the NULL string, no field splitting is done; if
     the parameter is unset, the default value of space, tab, and newline is
     used.

     Also, note that the field splitting applies only to the immediate result
     of the substitution. Using the previous example, the substitution for
     $VAR:E results in the fields: 'A', 'B', '', and 'D:E', not 'A', 'B', '',
     'D', and 'E'. This behavior is POSIX compliant, but incompatible with
     some other shell implementations which do field splitting on the word
     which contained the substitution or use IFS as a general whitespace del-
     imiter.

     The results of substitution are, unless otherwise specified, also subject
     to brace expansion and file name expansion (see the relevant sections
     below).

     A command substitution is replaced by the output generated by the speci-
     fied command which is run in a subshell. For $(command) and ${ command;}
     substitutions, normal quoting rules are used when command is parsed; how-
     ever, for the deprecated `command` form, a '\' followed by any of '$',
     '`', or '\' is stripped (a '\' followed by any other character is un-
     changed). As a special case in command substitutions, a command of the
     form <file is interpreted to mean substitute the contents of file. Note
     that $(<foo) has the same effect as $(cat foo).

     Note that some shells do not use a recursive parser for command substitu-
     tions, leading to failure for certain constructs; to be portable, use as
     workaround 'x=$(cat) <<"EOF"' (or the newline-keeping 'x=<<"EOF"' exten-
     sion) instead to merely slurp the string. IEEE Std 1003.1 ("POSIX")
     recommends to use case statements of the form 'x=$(case $foo in (bar)
     echo $bar ;; (*) echo $baz ;; esac)' instead, which would work but not
     serve as example for this portability issue.

           x=$(case $foo in bar) echo $bar ;; *) echo $baz ;; esac)
           # above fails to parse on old shells; below is the workaround
           x=$(eval $(cat)) <<"EOF"
           case $foo in bar) echo $bar ;; *) echo $baz ;; esac
           EOF

     Arithmetic substitutions are replaced by the value of the specified ex-
     pression. For example, the command print $((2+3*4)) displays 14. See
     Arithmetic expressions for a description of an expression.

Parameters

     Parameters are shell variables; they can be assigned values and their
     values can be accessed using a parameter substitution. A parameter name
     is either one of the special single punctuation or digit character param-
     eters described below, or a letter followed by zero or more letters or
     digits ('_' counts as a letter). The latter form can be treated as arrays
     by appending an array index of the form [expr] where expr is an arithmet-
     ic expression. Array indices in mksh are limited to the range 0 through
     4294967295, inclusive. That is, they are a 32-bit unsigned integer.

     Parameter substitutions take the form $name, ${name}, or ${name[expr]}
     where name is a parameter name. Substitution of all array elements with
     ${name[*]} and ${name[@]} works equivalent to $* and $@ for positional
     parameters. If substitution is performed on a parameter (or an array
     parameter element) that is not set, a null string is substituted unless
     the nounset option (set -o nounset or set -u) is set, in which case an
     error occurs.

     Parameters can be assigned values in a number of ways. First, the shell
     implicitly sets some parameters like '#', 'PWD', and '$'; this is the
     only way the special single character parameters are set. Second, parame-
     ters are imported from the shell's environment at startup. Third, parame-
     ters can be assigned values on the command line: for example, FOO=bar
     sets the parameter "FOO" to "bar"; multiple parameter assignments can be
     given on a single command line and they can be followed by a simple-
     command, in which case the assignments are in effect only for the dura-
     tion of the command (such assignments are also exported; see below for
     the implications of this). Note that both the parameter name and the '='
     must be unquoted for the shell to recognise a parameter assignment. The
     construct FOO+=baz is also recognised; the old and new values are immedi-
     ately concatenated. The fourth way of setting a parameter is with the
     export, global, readonly, and typeset commands; see their descriptions in
     the Command execution section. Fifth, for and select loops set parameters
     as well as the getopts, read, and set -A commands. Lastly, parameters can
     be assigned values using assignment operators inside arithmetic expres-
     sions (see Arithmetic expressions below) or using the ${name=value} form
     of the parameter substitution (see below).

     Parameters with the export attribute (set using the export or typeset -x
     commands, or by parameter assignments followed by simple commands) are
     put in the environment (see environ(7)) of commands run by the shell as
     name=value pairs. The order in which parameters appear in the environment
     of a command is unspecified. When the shell starts up, it extracts param-
     eters and their values from its environment and automatically sets the
     export attribute for those parameters.

     Modifiers can be applied to the ${name} form of parameter substitution:

     ${name:-word}
             If name is set and not NULL, it is substituted; otherwise, word
             is substituted.

     ${name:+word}
             If name is set and not NULL, word is substituted; otherwise,
             nothing is substituted.

     ${name:=word}
             If name is set and not NULL, it is substituted; otherwise, it is
             assigned word and the resulting value of name is substituted.

     ${name:?word}
             If name is set and not NULL, it is substituted; otherwise, word
             is printed on standard error (preceded by name:) and an error oc-
             curs (normally causing termination of a shell script, function,
             or script sourced using the '.' built-in). If word is omitted,
             the string "parameter null or not set" is used instead. Currently
             a bug, if word is a variable which expands to the null string,
             the error message is also printed.

     Note that, for all of the above, word is actually considered quoted, and
     special parsing rules apply. The parsing rules also differ on whether the
     expression is double-quoted: word then uses double-quoting rules, except
     for the double quote itself ('"') and the closing brace, which, if
     backslash escaped, gets quote removal applied.

     In the above modifiers, the ':' can be omitted, in which case the condi-
     tions only depend on name being set (as opposed to set and not NULL). If
     word is needed, parameter, command, arithmetic, and tilde substitution
     are performed on it; if word is not needed, it is not evaluated.

     The following forms of parameter substitution can also be used (if name
     is an array, its element #0 will be substituted in a scalar context):

     ${#name}
             The number of positional parameters if name is '*', '@', or not
             specified; otherwise the length (in characters) of the string
             value of parameter name.

     ${#name[*]}
     ${#name[@]}
             The number of elements in the array name.

     ${%name}
             The width (in screen columns) of the string value of parameter
             name, or -1 if ${name} contains a control character.

     ${!name}
             The name of the variable referred to by name. This will be name
             except when name is a name reference (bound variable), created by
             the nameref command (which is an alias for typeset -n).

     ${!name[*]}
     ${!name[@]}
             The names of indices (keys) in the array name.

     ${name#pattern}
     ${name##pattern}
             If pattern matches the beginning of the value of parameter name,
             the matched text is deleted from the result of substitution. A
             single '#' results in the shortest match, and two of them result
             in the longest match. Cannot be applied to a vector (${*} or ${@}
             or ${array[*]} or ${array[@]}).

     ${name%pattern}
     ${name%%pattern}
             Like ${..#..} substitution, but it deletes from the end of the
             value. Cannot be applied to a vector.

     ${name/pattern/string}
     ${name//pattern/string}
             Like ${..#..} substitution, but it replaces the longest match of
             pattern, anchored anywhere in the value, with string. If pattern
             begins with '#', it is anchored at the beginning of the value; if
             it begins with '%', it is anchored at the end. Patterns that are
             empty or consist only of wildcards are invalid. A single '/' re-
             places the first occurence of the search pattern, and two of them
             replace all occurences. If /string is omitted, the pattern is re-
             placed by the empty string, i.e. deleted. Cannot be applied to a
             vector. Inefficiently implemented, may be slow.

     ${name:pos:len}
             The first len characters of name, starting at position pos, are
             substituted. Both pos and :len are optional. If pos is negative,
             counting starts at the end of the string; if it is omitted, it
             defaults to 0. If len is omitted or greater than the length of
             the remaining string, all of it is substituted. Both pos and len
             are evaluated as arithmetic expressions. Currently, pos must
             start with a space, opening parenthesis or digit to be recog-
             nised. Cannot be applied to a vector.

     ${name@#}
             The hash (using the BAFH algorithm) of the expansion of name.
             This is also used internally for the shell's hashtables.

     ${name@Q}
             A quoted expression safe for re-entry, whose value is the value
             of the name parameter, is substituted.

     Note that pattern may need extended globbing pattern (@(...)), single
     ('...') or double ("...") quote escaping unless -o sh is set.

     The following special parameters are implicitly set by the shell and can-
     not be set directly using assignments:

     !       Process ID of the last background process started. If no back-
             ground processes have been started, the parameter is not set.

     #       The number of positional parameters ($1, $2, etc.).

     $       The PID of the shell, or the PID of the original shell if it is a
             subshell. Do NOT use this mechanism for generating temporary file
             names; see mktemp(1) instead.

     -       The concatenation of the current single letter options (see the
             set command below for a list of options).

     ?       The exit status of the last non-asynchronous command executed. If
             the last command was killed by a signal, $? is set to 128 plus
             the signal number.

     0       The name of the shell, determined as follows: the first argument
             to mksh if it was invoked with the -c option and arguments were
             given; otherwise the file argument, if it was supplied; or else
             the basename the shell was invoked with (i.e. argv[0]). $0 is
             also set to the name of the current script or the name of the
             current function, if it was defined with the function keyword
             (i.e. a Korn shell style function).

     1 .. 9  The first nine positional parameters that were supplied to the
             shell, function, or script sourced using the '.' built-in. Furth-
             er positional parameters may be accessed using ${number}.

     *       All positional parameters (except 0), i.e. $1, $2, $3, ...
             If used outside of double quotes, parameters are separate words
             (which are subjected to word splitting); if used within double
             quotes, parameters are separated by the first character of the
             IFS parameter (or the empty string if IFS is NULL).

     @       Same as $*, unless it is used inside double quotes, in which case
             a separate word is generated for each positional parameter. If
             there are no positional parameters, no word is generated. $@ can
             be used to access arguments, verbatim, without losing NULL argu-
             ments or splitting arguments with spaces.

     The following parameters are set and/or used by the shell:

     _            (underscore) When an external command is executed by the
                  shell, this parameter is set in the environment of the new
                  process to the path of the executed command. In interactive
                  use, this parameter is also set in the parent shell to the
                  last word of the previous command.

     BASHPID      The PID of the shell or subshell.

     CDPATH       Search path for the cd built-in command. It works the same
                  way as PATH for those directories not beginning with '/' in
                  cd commands. Note that if CDPATH is set and does not contain
                  '.' or contains an empty path, the current directory is not
                  searched. Also, the cd built-in command will display the
                  resulting directory when a match is found in any search path
                  other than the empty path.

     COLUMNS      Set to the number of columns on the terminal or window. Al-
                  ways set, defaults to 80, unless the value as reported by
                  stty(1) is non-zero and sane enough (minimum is 12x3); simi-
                  lar for LINES. This parameter is used by the interactive
                  line editing modes, and by the select, set -o, and kill -l
                  commands to format information columns. Importing from the
                  environment or unsetting this parameter removes the binding
                  to the actual terminal size in favour of the provided value.

     ENV          If this parameter is found to be set after any profile files
                  are executed, the expanded value is used as a shell startup
                  file. It typically contains function and alias definitions.

     ERRNO        Integer value of the shell's errno variable. It indicates
                  the reason the last system call failed. Not yet implemented.

     EXECSHELL    If set, this parameter is assumed to contain the shell that
                  is to be used to execute commands that execve(2) fails to
                  execute and which do not start with a "#!shell" sequence.

     FCEDIT       The editor used by the fc command (see below).

     FPATH        Like PATH, but used when an undefined function is executed
                  to locate the file defining the function. It is also
                  searched when a command can't be found using PATH. See
                  Functions below for more information.

     HISTFILE     The name of the file used to store command history. When as-
                  signed to, history is loaded from the specified file. Also,
                  several invocations of the shell will share history if their
                  HISTFILE parameters all point to the same file.

                  Note: If HISTFILE isn't set, no history file is used. This
                  is different from AT&T UNIX ksh.

     HISTSIZE     The number of commands normally stored for history. The de-
                  fault is 2047.

     HOME         The default directory for the cd command and the value sub-
                  stituted for an unqualified ~ (see Tilde expansion below).

     IFS          Internal field separator, used during substitution and by
                  the read command, to split values into distinct arguments;
                  normally set to space, tab, and newline. See Substitution
                  above for details.

                  Note: This parameter is not imported from the environment
                  when the shell is started.

     KSHEGID      The effective group id of the shell.

     KSHGID       The real group id of the shell.

     KSHUID       The real user id of the shell.

     KSH_VERSION  The name and version of the shell (read-only). See also the
                  version commands in Emacs editing mode and Vi editing mode
                  sections, below.

     LINENO       The line number of the function or shell script that is
                  currently being executed.

     LINES        Set to the number of lines on the terminal or window. Always
                  set, defaults to 24. See COLUMNS.

     EPOCHREALTIME
                  Time since the epoch, as returned by gettimeofday(2), for-
                  matted as decimal tv_sec followed by a dot ('.') and tv_usec
                  padded to exactly six decimal digits.

     OLDPWD       The previous working directory. Unset if cd has not success-
                  fully changed directories since the shell started, or if the
                  shell doesn't know where it is.

     OPTARG       When using getopts, it contains the argument for a parsed
                  option, if it requires one.

     OPTIND       The index of the next argument to be processed when using
                  getopts. Assigning 1 to this parameter causes getopts to
                  process arguments from the beginning the next time it is in-
                  voked.

     PATH         A colon separated list of directories that are searched when
                  looking for commands and files sourced using the '.' command
                  (see below). An empty string resulting from a leading or
                  trailing colon, or two adjacent colons, is treated as a '.'
                  (the current directory).

     PGRP         The process ID of the shell's process group leader.

     PIPESTATUS   An array containing the errorlevel (exit status) codes, one
                  by one, of the last pipeline run in the foreground.

     PPID         The process ID of the shell's parent.

     PS1          The primary prompt for interactive shells. Parameter, com-
                  mand, and arithmetic substitutions are performed, and '!' is
                  replaced with the current command number (see the fc command
                  below). A literal '!' can be put in the prompt by placing
                  '!!' in PS1.

                  The default prompt is '$ ' for non-root users, '# ' for
                  root. If mksh is invoked by root and PS1 does not contain a
                  '#' character, the default value will be used even if PS1
                  already exists in the environment.

                  The mksh distribution comes with a sample dot.mkshrc con-
                  taining a sophisticated example, but you might like the fol-
                  lowing one (note that ${HOSTNAME:=$(hostname)} and the
                  root-vs-user distinguishing clause are (in this example) ex-
                  ecuted at PS1 assignment time, while the $USER and $PWD are
                  escaped and thus will be evaluated each time a prompt is
                  displayed):

                  PS1='${USER:=$(id -un)}'"@${HOSTNAME:=$(hostname)}:\$PWD $(
                          if (( USER_ID )); then print \$; else print \#; fi) "

                  Note that since the command-line editors try to figure out
                  how long the prompt is (so they know how far it is to the
                  edge of the screen), escape codes in the prompt tend to mess
                  things up. You can tell the shell not to count certain se-
                  quences (such as escape codes) by prefixing your prompt with
                  a character (such as Ctrl-A) followed by a carriage return
                  and then delimiting the escape codes with this character.
                  Any occurences of that character in the prompt are not
                  printed. By the way, don't blame me for this hack; it's
                  derived from the original ksh88(1), which did print the del-
                  imiter character so you were out of luck if you did not have
                  any non-printing characters.

                  Since Backslashes and other special characters may be inter-
                  preted by the shell, to set PS1 either escape the backslash
                  itself, or use double quotes. The latter is more practical.
                  This is a more complex example, avoiding to directly enter
                  special characters (for example with ^V in the emacs editing
                  mode), which embeds the current working directory, in re-
                  verse video (colour would work, too), in the prompt string:

                        x=$(print \\001)
                        PS1="$x$(print \\r)$x$(tput so)$x\$PWD$x$(tput se)$x> "

                  Due to a strong suggestion from David G. Korn, mksh now also
                  supports the following form:

                        PS1=$'\1\r\1\e[7m\1$PWD\1\e[0m\1> '

     PS2          Secondary prompt string, by default '> ', used when more in-
                  put is needed to complete a command.

     PS3          Prompt used by the select statement when reading a menu
                  selection. The default is '#? '.

     PS4          Used to prefix commands that are printed during execution
                  tracing (see the set -x command below). Parameter, command,
                  and arithmetic substitutions are performed before it is
                  printed. The default is '+ '. You may want to set it to
                  '[$EPOCHREALTIME] ' instead, to include timestamps.

     PWD          The current working directory. May be unset or NULL if the
                  shell doesn't know where it is.

     RANDOM       Each time RANDOM is referenced, it is assigned a number
                  between 0 and 32767 from a Linear Congruential PRNG first.

     REPLY        Default parameter for the read command if no names are
                  given. Also used in select loops to store the value that is
                  read from standard input.

     SECONDS      The number of seconds since the shell started or, if the
                  parameter has been assigned an integer value, the number of
                  seconds since the assignment plus the value that was as-
                  signed.

     TMOUT        If set to a positive integer in an interactive shell, it
                  specifies the maximum number of seconds the shell will wait
                  for input after printing the primary prompt (PS1). If the
                  time is exceeded, the shell exits.

     TMPDIR       The directory temporary shell files are created in. If this
                  parameter is not set, or does not contain the absolute path
                  of a writable directory, temporary files are created in
                  /tmp.

     USER_ID      The effective user id of the shell.

Tilde expansion

     Tilde expansion which is done in parallel with parameter substitution, is
     done on words starting with an unquoted '~'. The characters following the
     tilde, up to the first '/', if any, are assumed to be a login name. If
     the login name is empty, '+', or '-', the value of the HOME, PWD, or
     OLDPWD parameter is substituted, respectively. Otherwise, the password
     file is searched for the login name, and the tilde expression is substi-
     tuted with the user's home directory. If the login name is not found in
     the password file or if any quoting or parameter substitution occurs in
     the login name, no substitution is performed.

     In parameter assignments (such as those preceding a simple-command or
     those occurring in the arguments of alias, export, global, readonly, and
     typeset), tilde expansion is done after any assignment (i.e. after the
     equals sign) or after an unquoted colon (':'); login names are also del-
     imited by colons.

     The home directory of previously expanded login names are cached and re-
     used. The alias -d command may be used to list, change, and add to this
     cache (e.g. alias -d fac=/usr/local/facilities; cd ~fac/bin).

Brace expansion (alteration)

     Brace expressions take the following form:

           prefix{str1,...,strN}suffix

     The expressions are expanded to N words, each of which is the concatena-
     tion of prefix, stri, and suffix (e.g. "a{c,b{X,Y},d}e" expands to four
     words: "ace", "abXe", "abYe", and "ade"). As noted in the example, brace
     expressions can be nested and the resulting words are not sorted. Brace
     expressions must contain an unquoted comma (',') for expansion to occur
     (e.g. {} and {foo} are not expanded). Brace expansion is carried out
     after parameter substitution and before file name generation.

File name patterns

     A file name pattern is a word containing one or more unquoted '?', '*',
     '+', '@', or '!' characters or "[..]" sequences. Once brace expansion has
     been performed, the shell replaces file name patterns with the sorted
     names of all the files that match the pattern (if no files match, the
     word is left unchanged). The pattern elements have the following meaning:

     ?       Matches any single character.

     *       Matches any sequence of octets.

     [..]    Matches any of the octets inside the brackets. Ranges of octets
             can be specified by separating two octets by a '-' (e.g. "[a0-9]"
             matches the letter 'a' or any digit). In order to represent it-
             self, a '-' must either be quoted or the first or last octet in
             the octet list. Similarly, a ']' must be quoted or the first oc-
             tet in the list if it is to represent itself instead of the end
             of the list. Also, a '!' appearing at the start of the list has
             special meaning (see below), so to represent itself it must be
             quoted or appear later in the list.

     [!..]   Like [..], except it matches any octet not inside the brackets.

     *(pattern|...|pattern)
             Matches any string of octets that matches zero or more oc-
             currences of the specified patterns. Example: The pattern
             *(foo|bar) matches the strings "", "foo", "bar", "foobarfoo",
             etc.

     +(pattern|...|pattern)
             Matches any string of octets that matches one or more occurrences
             of the specified patterns. Example: The pattern +(foo|bar)
             matches the strings "foo", "bar", "foobar", etc.

     ?(pattern|...|pattern)
             Matches the empty string or a string that matches one of the
             specified patterns. Example: The pattern ?(foo|bar) only matches
             the strings "", "foo", and "bar".

     @(pattern|...|pattern)
             Matches a string that matches one of the specified patterns. Ex-
             ample: The pattern @(foo|bar) only matches the strings "foo" and
             "bar".

     !(pattern|...|pattern)
             Matches any string that does not match one of the specified pat-
             terns. Examples: The pattern !(foo|bar) matches all strings ex-
             cept "foo" and "bar"; the pattern !(*) matches no strings; the
             pattern !(?)* matches all strings (think about it).

     Note that complicated globbing, especially with alternatives, is slow;
     using separate comparisons may (or may not) be faster.

     Note that mksh (and pdksh) never matches '.' and '..', but AT&T UNIX ksh,
     Bourne sh, and GNU bash do.

     Note that none of the above pattern elements match either a period ('.')
     at the start of a file name or a slash ('/'), even if they are explicitly
     used in a [..] sequence; also, the names '.' and '..' are never matched,
     even by the pattern '.*'.

     If the markdirs option is set, any directories that result from file name
     generation are marked with a trailing '/'.

Input/output redirection

     When a command is executed, its standard input, standard output, and
     standard error (file descriptors 0, 1, and 2, respectively) are normally
     inherited from the shell. Three exceptions to this are commands in pipe-
     lines, for which standard input and/or standard output are those set up
     by the pipeline, asynchronous commands created when job control is dis-
     abled, for which standard input is initially set to be from /dev/null,
     and commands for which any of the following redirections have been speci-
     fied:

     > file      Standard output is redirected to file. If file does not ex-
                 ist, it is created; if it does exist, is a regular file, and
                 the noclobber option is set, an error occurs; otherwise, the
                 file is truncated. Note that this means the command cmd <foo
                 >foo will open foo for reading and then truncate it when it
                 opens it for writing, before cmd gets a chance to actually
                 read foo.

     >| file     Same as >, except the file is truncated, even if the
                 noclobber option is set.

     >> file     Same as >, except if file exists it is appended to instead of
                 being truncated. Also, the file is opened in append mode, so
                 writes always go to the end of the file (see open(2)).

     < file      Standard input is redirected from file, which is opened for
                 reading.

     <> file     Same as <, except the file is opened for reading and writing.

     << marker   After reading the command line containing this kind of
                 redirection (called a "here document"), the shell copies
                 lines from the command source into a temporary file until a
                 line matching marker is read. When the command is executed,
                 standard input is redirected from the temporary file. If
                 marker contains no quoted characters, the contents of the
                 temporary file are processed as if enclosed in double quotes
                 each time the command is executed, so parameter, command, and
                 arithmetic substitutions are performed, along with backslash
                 ('\') escapes for '$', '`', '\', and '\newline', but not for
                 '"'. If multiple here documents are used on the same command
                 line, they are saved in order.

                 If no marker is given, the here document ends at the next <<
                 and substitution will be performed. If marker is only a set
                 of either single "''" or double '""' quotes with nothing in
                 between, the here document ends at the next empty line and
                 substitution will not be performed.

     <<- marker  Same as <<, except leading tabs are stripped from lines in
                 the here document.

     <<< word    Same as <<, except that word is the here document. This is
                 called a here string.

     <& fd       Standard input is duplicated from file descriptor fd. fd can
                 be a number, indicating the number of an existing file
                 descriptor; the letter 'p', indicating the file descriptor
                 associated with the output of the current co-process; or the
                 character '-', indicating standard input is to be closed.
                 Note that fd is limited to a single digit in most shell im-
                 plementations.

     >& fd       Same as <&, except the operation is done on standard output.

     &> file     Same as > file 2>&1. This is a GNU bash extension supported
                 by mksh which also supports the preceding explicit fd number,
                 for example, 3&> file is the same as 3> file 2>&3 in mksh but
                 a syntax error in GNU bash. Setting the -o posix or -o sh
                 shell options disable parsing of this redirection; it's a
                 compatibility feature to legacy scripts, to not be used when
                 writing new shell code.

     &>| file, &>> file, &>& fd
                 Same as >| file, >> file, or >& fd, followed by 2>&1, as
                 above. These are mksh extensions.

     In any of the above redirections, the file descriptor that is redirected
     (i.e. standard input or standard output) can be explicitly given by
     preceding the redirection with a number (portably, only a single digit).
     Parameter, command, and arithmetic substitutions, tilde substitutions,
     and (if the shell is interactive) file name generation are all performed
     on the file, marker, and fd arguments of redirections. Note, however,
     that the results of any file name generation are only used if a single
     file is matched; if multiple files match, the word with the expanded file
     name generation characters is used. Note that in restricted shells,
     redirections which can create files cannot be used.

     For simple-commands, redirections may appear anywhere in the command; for
     compound-commands (if statements, etc.), any redirections must appear at
     the end. Redirections are processed after pipelines are created and in
     the order they are given, so the following will print an error with a
     line number prepended to it:

           $ cat /foo/bar 2>&1 >/dev/null | pr -n -t

     File descriptors created by input/output redirections are private to the
     Korn shell, but passed to sub-processes if -o posix or -o sh is set.

Arithmetic expressions

     Integer arithmetic expressions can be used with the let command, inside
     $((..)) expressions, inside array references (e.g. name[expr]), as numer-
     ic arguments to the test command, and as the value of an assignment to an
     integer parameter.

     Expressions are calculated using signed arithmetic and the mksh_ari_t
     type (a 32-bit signed integer), unless they begin with a sole '#' charac-
     ter, in which case they use mksh_uari_t (a 32-bit unsigned integer).

     Expressions may contain alpha-numeric parameter identifiers, array refer-
     ences, and integer constants and may be combined with the following C
     operators (listed and grouped in increasing order of precedence):

     Unary operators:

           + - ! ~ ++ --

     Binary operators:

           ,
           = += -= *= /= %= <<<= >>>= <<= >>= &= ^= |=
           ||
           &&
           |
           ^
           &
           == !=
           < <= > >=
           <<< >>> << >>
           + -
           * / %

     Ternary operators:

           ?: (precedence is immediately higher than assignment)

     Grouping operators:

           ( )

     Integer constants and expressions are calculated using an exactly 32-bit
     wide, signed or unsigned, type with silent wraparound on integer over-
     flow. Integer constants may be specified with arbitrary bases using the
     notation base#number, where base is a decimal integer specifying the
     base, and number is a number in the specified base. Additionally, base-16
     integers may be specified by prefixing them with '0x' (case-insensitive)
     in all forms of arithmetic expressions, except as numeric arguments to
     the test built-in command. Prefixing numbers with a sole digit zero ('0')
     leads to the shell interpreting it as base-8 (octal) integer in posix
     mode only; historically, (pd)ksh has never done so either anyway, and
     it's unsafe to do that, but POSIX demands it nowadays. As a special mksh
     extension, numbers to the base of one are treated as either (8-bit tran-
     sparent) ASCII or Unicode codepoints, depending on the shell's utf8-mode
     flag (current setting). The AT&T UNIX ksh93 syntax of "'x'" instead of
     "1#x" is also supported. Note that NUL bytes (integral value of zero)
     cannot be used. An unset or empty parameter evaluates to 0 in integer
     context. In Unicode mode, raw octets are mapped into the range EF80..EFFF
     as in OPTU-8, which is in the PUA and has been assigned by CSUR for this
     use. If more than one octet in ASCII mode, or a sequence of more than one
     octet not forming a valid and minimal CESU-8 sequence is passed, the
     behaviour is undefined (usually, the shell aborts with a parse error, but
     rarely, it succeeds, e.g. on the sequence C2 20). That's why you should
     always use ASCII mode unless you know that the input is well-formed UTF-8
     in the range of 0000..FFFD.

     The operators are evaluated as follows:

           unary +
                   Result is the argument (included for completeness).

           unary -
                   Negation.

           !       Logical NOT; the result is 1 if argument is zero, 0 if not.

           ~       Arithmetic (bit-wise) NOT.

           ++      Increment; must be applied to a parameter (not a literal or
                   other expression). The parameter is incremented by 1. When
                   used as a prefix operator, the result is the incremented
                   value of the parameter; when used as a postfix operator,
                   the result is the original value of the parameter.

           --      Similar to ++, except the parameter is decremented by 1.

           ,       Separates two arithmetic expressions; the left-hand side is
                   evaluated first, then the right. The result is the value of
                   the expression on the right-hand side.

           =       Assignment; the variable on the left is set to the value on
                   the right.

           += -= *= /= %= <<<= >>>= <<= >>= &= ^= |=
                   Assignment operators. <var><op>=<expr> is the same as
                   <var>=<var><op><expr>, with any operator precedence in
                   <expr> preserved. For example, "var1 *= 5 + 3" is the same
                   as specifying "var1 = var1 * (5 + 3)".

           ||      Logical OR; the result is 1 if either argument is non-zero,
                   0 if not. The right argument is evaluated only if the left
                   argument is zero.

           &&      Logical AND; the result is 1 if both arguments are non-
                   zero, 0 if not. The right argument is evaluated only if the
                   left argument is non-zero.

           |       Arithmetic (bit-wise) OR.

           ^       Arithmetic (bit-wise) XOR (exclusive-OR).

           &       Arithmetic (bit-wise) AND.

           ==      Equal; the result is 1 if both arguments are equal, 0 if
                   not.

           !=      Not equal; the result is 0 if both arguments are equal, 1
                   if not.

           <       Less than; the result is 1 if the left argument is less
                   than the right, 0 if not.

           <= > >=
                   Less than or equal, greater than, greater than or equal.
                   See <.

           <<< >>>
                   Rotate left (right); the result is similar to shift (see
                   <<) except that the bits shifted out at one end are shifted
                   in at the other end, instead of zero or sign bits.

           << >>   Shift left (right); the result is the left argument with
                   its bits shifted left (right) by the amount given in the
                   right argument.

           + - * /
                   Addition, subtraction, multiplication, and division.

           %       Remainder; the result is the remainder of the division of
                   the left argument by the right.

           <arg1>?<arg2>:<arg3>
                   If <arg1> is non-zero, the result is <arg2>; otherwise the
                   result is <arg3>. The non-result argument is not evaluated.

Co-processes

     A co-process (which is a pipeline created with the '|&' operator) is an
     asynchronous process that the shell can both write to (using print -p)
     and read from (using read -p). The input and output of the co-process can
     also be manipulated using >&p and <&p redirections, respectively. Once a
     co-process has been started, another can't be started until the co-
     process exits, or until the co-process's input has been redirected using
     an exec n>&p redirection. If a co-process's input is redirected in this
     way, the next co-process to be started will share the output with the
     first co-process, unless the output of the initial co-process has been
     redirected using an exec n<&p redirection.

     Some notes concerning co-processes:

     •   The only way to close the co-process's input (so the co-process reads
         an end-of-file) is to redirect the input to a numbered file descrip-
         tor and then close that file descriptor: exec 3>&p; exec 3>&-

     •   In order for co-processes to share a common output, the shell must
         keep the write portion of the output pipe open. This means that end-
         of-file will not be detected until all co-processes sharing the co-
         process's output have exited (when they all exit, the shell closes
         its copy of the pipe). This can be avoided by redirecting the output
         to a numbered file descriptor (as this also causes the shell to close
         its copy). Note that this behaviour is slightly different from the
         original Korn shell which closes its copy of the write portion of the
         co-process output when the most recently started co-process (instead
         of when all sharing co-processes) exits.

     •   print -p will ignore SIGPIPE signals during writes if the signal is
         not being trapped or ignored; the same is true if the co-process in-
         put has been duplicated to another file descriptor and print -un is
         used.

Functions

     Functions are defined using either Korn shell function function-name syn-
     tax or the Bourne/POSIX shell function-name() syntax (see below for the
     difference between the two forms). Functions are like .-scripts (i.e.
     scripts sourced using the '.' built-in) in that they are executed in the
     current environment. However, unlike .-scripts, shell arguments (i.e. po-
     sitional parameters $1, $2, etc.) are never visible inside them. When the
     shell is determining the location of a command, functions are searched
     after special built-in commands, before builtins and the PATH is
     searched.

     An existing function may be deleted using unset -f function-name. A list
     of functions can be obtained using typeset +f and the function defini-
     tions can be listed using typeset -f. The autoload command (which is an
     alias for typeset -fu) may be used to create undefined functions: when an
     undefined function is executed, the shell searches the path specified in
     the FPATH parameter for a file with the same name as the function which,
     if found, is read and executed. If after executing the file the named
     function is found to be defined, the function is executed; otherwise, the
     normal command search is continued (i.e. the shell searches the regular
     built-in command table and PATH). Note that if a command is not found us-
     ing PATH, an attempt is made to autoload a function using FPATH (this is
     an undocumented feature of the original Korn shell).

     Functions can have two attributes, "trace" and "export", which can be set
     with typeset -ft and typeset -fx, respectively. When a traced function is
     executed, the shell's xtrace option is turned on for the function's dura-
     tion. The "export" attribute of functions is currently not used. In the
     original Korn shell, exported functions are visible to shell scripts that
     are executed.

     Since functions are executed in the current shell environment, parameter
     assignments made inside functions are visible after the function com-
     pletes. If this is not the desired effect, the typeset command can be
     used inside a function to create a local parameter. Note that AT&T UNIX
     ksh93 uses static scoping (one global scope, one local scope per func-
     tion) and allows local variables only on Korn style functions, whereas
     mksh uses dynamic scoping (nested scopes of varying locality). Note that
     special parameters (e.g. $$, $!) can't be scoped in this way.

     The exit status of a function is that of the last command executed in the
     function. A function can be made to finish immediately using the return
     command; this may also be used to explicitly specify the exit status.

     Functions defined with the function reserved word are treated differently
     in the following ways from functions defined with the () notation:

     •   The $0 parameter is set to the name of the function (Bourne-style
         functions leave $0 untouched).

     •   Parameter assignments preceding function calls are not kept in the
         shell environment (executing Bourne-style functions will keep assign-
         ments).

     •   OPTIND is saved/reset and restored on entry and exit from the func-
         tion so getopts can be used properly both inside and outside the
         function (Bourne-style functions leave OPTIND untouched, so using
         getopts inside a function interferes with using getopts outside the
         function).

     •   Bourne-style function definitions take precedence over alias derefer-
         ences and remove alias definitions upon encounter, while aliases take
         precedence over Korn-style functions.

     In the future, the following differences may also be added:

     •   A separate trap/signal environment will be used during the execution
         of functions. This will mean that traps set inside a function will
         not affect the shell's traps and signals that are not ignored in the
         shell (but may be trapped) will have their default effect in a func-
         tion.

     •   The EXIT trap, if set in a function, will be executed after the func-
         tion returns.

Command execution

     After evaluation of command-line arguments, redirections, and parameter
     assignments, the type of command is determined: a special built-in com-
     mand, a function, a normal builtin, or the name of a file to execute
     found using the PATH parameter. The checks are made in the above order.
     Special built-in commands differ from other commands in that the PATH
     parameter is not used to find them, an error during their execution can
     cause a non-interactive shell to exit, and parameter assignments that are
     specified before the command are kept after the command completes. Regu-
     lar built-in commands are different only in that the PATH parameter is
     not used to find them.

     The original ksh and POSIX differ somewhat in which commands are con-
     sidered special or regular.

     POSIX special built-in utilities:

     ., :, break, continue, eval, exec, exit, export, readonly, return, set,
     shift, times, trap, unset

     Additional mksh commands keeping assignments:

     builtin, global, typeset, wait

     Builtins that are not special:

     [, alias, bg, bind, cat, cd, command, echo, false, fc, fg, getopts, jobs,
     kill, let, mknod, print, pwd, read, realpath, rename, sleep, suspend,
     test, true, ulimit, umask, unalias, whence

     Once the type of command has been determined, any command-line parameter
     assignments are performed and exported for the duration of the command.

     The following describes the special and regular built-in commands:

     . file [arg ...]
            This is called the "dot" command. Execute the commands in file in
            the current environment. The file is searched for in the direc-
            tories of PATH. If arguments are given, the positional parameters
            may be used to access them while file is being executed. If no ar-
            guments are given, the positional parameters are those of the en-
            vironment the command is used in.

     : [...]
            The null command. Exit status is set to zero.

     [ expression ]
            See test.

     alias [-d | -t [-r] | +-x] [-p] [+] [name[=value] ...]
            Without arguments, alias lists all aliases. For any name without a
            value, the existing alias is listed. Any name with a value defines
            an alias (see Aliases above).

            When listing aliases, one of two formats is used. Normally,
            aliases are listed as name=value, where value is quoted. If op-
            tions were preceded with '+', or a lone '+' is given on the com-
            mand line, only name is printed.

            The -d option causes directory aliases which are used in tilde ex-
            pansion to be listed or set (see Tilde expansion above).

            If the -p option is used, each alias is prefixed with the string
            "alias ".

            The -t option indicates that tracked aliases are to be listed/set
            (values specified on the command line are ignored for tracked
            aliases). The -r option indicates that all tracked aliases are to
            be reset.

            The -x option sets (+x clears) the export attribute of an alias,
            or, if no names are given, lists the aliases with the export at-
            tribute (exporting an alias has no effect).

     bg [job ...]
            Resume the specified stopped job(s) in the background. If no jobs
            are specified, %+ is assumed. See Job control below for more in-
            formation.

     bind [-l]
            The current bindings are listed. If the -l flag is given, bind in-
            stead lists the names of the functions to which keys may be bound.
            See Emacs editing mode for more information.

     bind [-m] string=[substitute] ...
     bind string=[editing-command] ...
            The specified editing command is bound to the given string, which
            should consist of a control character optionally preceded by one
            of the two prefix characters and optionally succeded by a tilde
            character. Future input of the string will cause the editing com-
            mand to be immediately invoked. If the -m flag is given, the
            specified input string will afterwards be immediately replaced by
            the given substitute string which may contain editing commands but
            not other macros. If a tilde postfix is given, a tilde trailing
            the one or two prefices and the control character is ignored, any
            other trailing character will be processed afterwards.

            Control characters may be written using caret notation i.e. ^X
            represents Ctrl-X. Note that although only two prefix characters
            (usually ESC and ^X) are supported, some multi-character sequences
            can be supported.

            The following default bindings show how the arrow keys, the home,
            end and delete key on a BSD wsvt25, xterm-xfree86 or GNU screen
            terminal are bound (of course some escape sequences won't work out
            quite this nicely):

                  bind '^X'=prefix-2
                  bind '^[['=prefix-2
                  bind '^XA'=up-history
                  bind '^XB'=down-history
                  bind '^XC'=forward-char
                  bind '^XD'=backward-char
                  bind '^X1~'=beginning-of-line
                  bind '^X7~'=beginning-of-line
                  bind '^XH'=beginning-of-line
                  bind '^X4~'=end-of-line
                  bind '^X8~'=end-of-line
                  bind '^XF'=end-of-line
                  bind '^X3~'=delete-char-forward

     break [level]
            Exit the levelth inner-most for, select, until, or while loop.
            level defaults to 1.

     builtin [--] command [arg ...]
            Execute the built-in command command.

     cat [-u] [file ...]
            Read files sequentially, in command line order, and write them to
            standard output. If a file is a single dash ('-') or absent, read
            from standard input. Unless compiled with MKSH_NO_EXTERNAL_CAT, if
            any options are given, an external cat(1) utility is invoked in-
            stead if called from the shell. For direct builtin calls, the
            POSIX -u option is supported as a no-op.

     cd [-L] [dir]
     cd -P [-e] [dir]
     chdir [-eLP] [dir]
            Set the working directory to dir. If the parameter CDPATH is set,
            it lists the search path for the directory containing dir. A NULL
            path means the current directory. If dir is found in any component
            of the CDPATH search path other than the NULL path, the name of
            the new working directory will be written to standard output. If
            dir is missing, the home directory HOME is used. If dir is '-',
            the previous working directory is used (see the OLDPWD parameter).

            If the -L option (logical path) is used or if the physical option
            isn't set (see the set command below), references to '..' in dir
            are relative to the path used to get to the directory. If the -P
            option (physical path) is used or if the physical option is set,
            '..' is relative to the filesystem directory tree. The PWD and
            OLDPWD parameters are updated to reflect the current and old work-
            ing directory, respectively. If the -e option is set for physical
            filesystem traversal, and PWD could not be set, the exit code is
            1; greater than 1 if an error occurred, 0 otherwise.

     cd [-eLP] old new
     chdir [-eLP] old new
            The string new is substituted for old in the current directory,
            and the shell attempts to change to the new directory.

     command [-pVv] cmd [arg ...]
            If neither the -v nor -V option is given, cmd is executed exactly
            as if command had not been specified, with two exceptions: first-
            ly, cmd cannot be a shell function; and secondly, special built-in
            commands lose their specialness (i.e. redirection and utility er-
            rors do not cause the shell to exit, and command assignments are
            not permanent).

            If the -p option is given, a default search path is used instead
            of the current value of PATH, the actual value of which is system
            dependent.

            If the -v option is given, instead of executing cmd, information
            about what would be executed is given (and the same is done for
            arg ...). For special and regular built-in commands and functions,
            their names are simply printed; for aliases, a command that de-
            fines them is printed; and for commands found by searching the
            PATH parameter, the full path of the command is printed. If no
            command is found (i.e. the path search fails), nothing is printed
            and command exits with a non-zero status. The -V option is like
            the -v option, except it is more verbose.

     continue [level]
            Jumps to the beginning of the levelth inner-most for, select,
            until, or while loop. level defaults to 1.

     echo [-Een] [arg ...]
            Warning: this utility is not portable; use the Korn shell builtin
            print instead.

            Prints its arguments (separated by spaces) followed by a newline,
            to the standard output. The newline is suppressed if any of the
            arguments contain the backslash sequence '\c'. See the print com-
            mand below for a list of other backslash sequences that are recog-
            nised.

            The options are provided for compatibility with BSD shell scripts.
            The -n option suppresses the trailing newline, -e enables
            backslash interpretation (a no-op, since this is normally done),
            and -E suppresses backslash interpretation.

            If the posix or sh option is set or this is a direct builtin call,
            only the first argument is treated as an option, and only if it is
            exactly "-n". Backslash interpretation is disabled.

     eval command ...
            The arguments are concatenated (with spaces between them) to form
            a single string which the shell then parses and executes in the
            current environment.

     exec [command [arg ...]]
            The command is executed without forking, replacing the shell pro-
            cess.

            If no command is given except for I/O redirection, the I/O
            redirection is permanent and the shell is not replaced. Any file
            descriptors greater than 2 which are opened or dup(2)'d in this
            way are not made available to other executed commands (i.e. com-
            mands that are not built-in to the shell). Note that the Bourne
            shell differs here; it does pass these file descriptors on.

     exit [status]
            The shell exits with the specified exit status. If status is not
            specified, the exit status is the current value of the $? parame-
            ter.

     export [-p] [parameter[=value]]
            Sets the export attribute of the named parameters. Exported param-
            eters are passed in the environment to executed commands. If
            values are specified, the named parameters are also assigned.

            If no parameters are specified, all parameters with the export at-
            tribute set are printed one per line; either their names, or, if a
            '-' with no option letter is specified, name=value pairs, or, with
            -p, export commands suitable for re-entry.

     false  A command that exits with a non-zero status.

     fc [-e editor | -l [-n]] [-r] [first [last]]
            first and last select commands from the history. Commands can be
            selected by history number (negative numbers go backwards from the
            current, most recent, line) or a string specifying the most recent
            command starting with that string. The -l option lists the command
            on standard output, and -n inhibits the default command numbers.
            The -r option reverses the order of the list. Without -l, the
            selected commands are edited by the editor specified with the -e
            option, or if no -e is specified, the editor specified by the
            FCEDIT parameter (if this parameter is not set, /bin/ed is used),
            and then executed by the shell.

     fc -e - | -s [-g] [old=new] [prefix]
            Re-execute the selected command (the previous command by default)
            after performing the optional substitution of old with new. If -g
            is specified, all occurrences of old are replaced with new. The
            meaning of -e - and -s is identical: re-execute the selected com-
            mand without invoking an editor. This command is usually accessed
            with the predefined: alias r='fc -e -'

     fg [job ...]
            Resume the specified job(s) in the foreground. If no jobs are
            specified, %+ is assumed. See Job control below for more informa-
            tion.

     getopts optstring name [arg ...]
            Used by shell procedures to parse the specified arguments (or po-
            sitional parameters, if no arguments are given) and to check for
            legal options. optstring contains the option letters that getopts
            is to recognise. If a letter is followed by a colon, the option is
            expected to have an argument. Options that do not take arguments
            may be grouped in a single argument. If an option takes an argu-
            ment and the option character is not the last character of the ar-
            gument it is found in, the remainder of the argument is taken to
            be the option's argument; otherwise, the next argument is the
            option's argument.

            Each time getopts is invoked, it places the next option in the
            shell parameter name and the index of the argument to be processed
            by the next call to getopts in the shell parameter OPTIND. If the
            option was introduced with a '+', the option placed in name is
            prefixed with a '+'. When an option requires an argument, getopts
            places it in the shell parameter OPTARG.

            When an illegal option or a missing option argument is encoun-
            tered, a question mark or a colon is placed in name (indicating an
            illegal option or missing argument, respectively) and OPTARG is
            set to the option character that caused the problem. Furthermore,
            if optstring does not begin with a colon, a question mark is
            placed in name, OPTARG is unset, and an error message is printed
            to standard error.

            When the end of the options is encountered, getopts exits with a
            non-zero exit status. Options end at the first (non-option argu-
            ment) argument that does not start with a '-', or when a '--' ar-
            gument is encountered.

            Option parsing can be reset by setting OPTIND to 1 (this is done
            automatically whenever the shell or a shell procedure is invoked).

            Warning: Changing the value of the shell parameter OPTIND to a
            value other than 1, or parsing different sets of arguments without
            resetting OPTIND, may lead to unexpected results.

     global ...
            See typeset.

     hash [-r] [name ...]
            Without arguments, any hashed executable command pathnames are
            listed. The -r option causes all hashed commands to be removed
            from the hash table. Each name is searched as if it were a command
            name and added to the hash table if it is an executable command.

     jobs [-lnp] [job ...]
            Display information about the specified job(s); if no jobs are
            specified, all jobs are displayed. The -n option causes informa-
            tion to be displayed only for jobs that have changed state since
            the last notification. If the -l option is used, the process ID of
            each process in a job is also listed. The -p option causes only
            the process group of each job to be printed. See Job control below
            for the format of job and the displayed job.

     kill [-s signame | -signum | -signame] { job | pid | pgrp } ...
            Send the specified signal to the specified jobs, process IDs, or
            process groups. If no signal is specified, the TERM signal is
            sent. If a job is specified, the signal is sent to the job's pro-
            cess group. See Job control below for the format of job.

     kill -l [exit-status ...]
            Print the signal name corresponding to exit-status. If no argu-
            ments are specified, a list of all the signals, their numbers, and
            a short description of them are printed.

     let [expression ...]
            Each expression is evaluated (see Arithmetic expressions above).
            If all expressions are successfully evaluated, the exit status is
            0 (1) if the last expression evaluated to non-zero (zero). If an
            error occurs during the parsing or evaluation of an expression,
            the exit status is greater than 1. Since expressions may need to
            be quoted, (( expr )) is syntactic sugar for let "expr".

     let]   Internally used alias for let.

     mknod [-m mode] name b|c major minor
     mknod [-m mode] name p
            Create a device special file. The file type may be b (block type
            device), c (character type device), or p (named pipe, FIFO). The
            file created may be modified according to its mode (via the -m op-
            tion), major (major device number), and minor (minor device
            number).

            See mknod(8) for further information.

     print [-nprsu[n] | -R [-en]] [argument ...]
            print prints its arguments on the standard output, separated by
            spaces and terminated with a newline. The -n option suppresses the
            newline. By default, certain C escapes are translated. These in-
            clude these mentioned in Backslash expansion above, as well as
            '\c', which is equivalent to using the -n option. Backslash expan-
            sion may be inhibited with the -r option. The -s option prints to
            the history file instead of standard output; the -u option prints
            to file descriptor n (n defaults to 1 if omitted); and the -p op-
            tion prints to the co-process (see Co-processes above).

            The -R option is used to emulate, to some degree, the BSD echo(1)
            command which does not process '\' sequences unless the -e option
            is given. As above, the -n option suppresses the trailing newline.

     printf format [arguments ...]
            Formatted output. Approximately the same as the printf(1), utili-
            ty, except it uses the same Backslash expansion and I/O code and
            does hot handle floating point as the rest of mksh. This is not
            normally part of mksh; however, distributors may have added this
            as builtin as a speed hack. Do not use in new code.

     pwd [-LP]
            Print the present working directory. If the -L option is used or
            if the physical option isn't set (see the set command below), the
            logical path is printed (i.e. the path used to cd to the current
            directory). If the -P option (physical path) is used or if the
            physical option is set, the path determined from the filesystem
            (by following '..' directories to the root directory) is printed.

     read [-A | -a] [-d x] [-N z | -n z] [-p | -u[n]] [-t n] [-rs] [p ...]
            Reads a line of input, separates the input into fields using the
            IFS parameter (see Substitution above), and assigns each field to
            the specified parameters p. If no parameters are specified, the
            REPLY parameter is used to store the result. With the -A and -a
            options, only no or one parameter is accepted. If there are more
            parameters than fields, the extra parameters are set to the empty
            string or 0; if there are more fields than parameters, the last
            parameter is assigned the remaining fields (including the word
            separators).

            The options are as follows:

            -A     Store the result into the parameter p (or REPLY) as array
                   of words.

            -a     Store the result without word splitting into the parameter
                   p (or REPLY) as array of characters (wide characters if the
                   utf8-mode option is enacted, octets otherwise).

            -d x   Use the first byte of x, NUL if empty, instead of the ASCII
                   newline character as input line delimiter.

            -N z   Instead of reading till end-of-line, read exactly z bytes;
                   less if EOF or a timeout occurs.

            -n z   Instead of reading till end-of-line, read up to z bytes but
                   return as soon as any bytes are read, e.g. from a slow ter-
                   minal device, or if EOF or a timeout occurs.

            -p     Read from the currently active co-process, see Co-processes
                   above for details on this.

            -u[n]  Read from the file descriptor n (defaults to 0, i.e. stan-
                   dard input). The argument must immediately follow the op-
                   tion character.

            -t n   Interrupt reading after n seconds (specified as positive
                   decimal value with an optional fractional part).

            -r     Normally, the ASCII backslash character escapes the special
                   meaning of the following character and is stripped from the
                   input; read does not stop when encountering a backslash-
                   newline sequence and does not store that newline in the
                   result. This option enables raw mode, in which backslashes
                   are not processed.

            -s     The input line is saved to the history.

            If the input is a terminal, both the -N and -n options set it into
            raw mode; they read an entire file if -1 is passed as z argument.

            The first parameter may have a question mark and a string appended
            to it, in which case the string is used as a prompt (printed to
            standard error before any input is read) if the input is a tty(4)
            (e.g. read nfoo?'number of foos: ').

            If no input is read or a timeout occurred, read exits with a non-
            zero status.

            Another handy set of tricks: If read is run in a loop such as
            while read foo; do ...; done then leading whitespace will be re-
            moved (IFS) and backslashes processed. You might want to use while
            IFS= read -r foo; do ...; done for pristine I/O. Similarily, when
            using the -a option, use of the -r option might be prudent; the
            same applies for:

                  find . -type f -print0 | \
                      while IFS= read -d '' -r filename; do
                          print -r -- "found <${filename#./}>"
                  done

            The inner loop will be executed in a subshell and variable changes
            cannot be propagated if executed in a pipeline:

                  bar | baz | while read foo; do ...; done

            Use co-processes instead:

                  bar | baz |&
                  while read -p foo; do ...; done
                  exec 3>&p; exec 3>&-

     readonly [-p] [parameter[=value] ...]
            Sets the read-only attribute of the named parameters. If values
            are given, parameters are set to them before setting the attri-
            bute. Once a parameter is made read-only, it cannot be unset and
            its value cannot be changed.

            If no parameters are specified, the names of all parameters with
            the read-only attribute are printed one per line, unless the -p
            option is used, in which case readonly commands defining all
            read-only parameters, including their values, are printed.

     realpath [--] name
            Prints the resolved absolute pathname corresponding to name. If
            name ends with a slash ('/'), it's also checked for existence and
            whether it is a directory; otherwise, realpath returns 0 if the
            pathname either exists or can be created immediately, i.e. all but
            the last component exist and are directories.

     rename [--] from to
            Renames the file from to to. Both must be complete pathnames and
            on the same device. This builtin is intended for emergency situa-
            tions where /bin/mv becomes unusable, and directly calls
            rename(2).

     return [status]
            Returns from a function or . script, with exit status status. If
            no status is given, the exit status of the last executed command
            is used. If used outside of a function or . script, it has the
            same effect as exit. Note that mksh treats both profile and ENV
            files as . scripts, while the original Korn shell only treats pro-
            files as . scripts.

     set [+-abCefhiklmnprsUuvXx] [+-o option] [+-A name] [--] [arg ...]
            The set command can be used to set (-) or clear (+) shell options,
            set the positional parameters, or set an array parameter. Options
            can be changed using the +-o option syntax, where option is the
            long name of an option, or using the +-letter syntax, where letter
            is the option's single letter name (not all options have a single
            letter name). The following table lists both option letters (if
            they exist) and long names along with a description of what the
            option does:

            -A name
                 Sets the elements of the array parameter name to arg ... If
                 -A is used, the array is reset (i.e. emptied) first; if +A is
                 used, the first N elements are set (where N is the number of
                 arguments); the rest are left untouched.

                 An alternative syntax for the command set -A foo -- a b c
                 which is compatible to GNU bash and also supported by AT&T
                 UNIX ksh93 is: foo=(a b c); foo+=(d e)

                 Another AT&T UNIX ksh93 and GNU bash extension allows speci-
                 fying the indices used for arg ... (from the above example, a
                 b c) like this: set -A foo -- [0]=a [1]=b [2]=c or foo=([0]=a
                 [1]=b [2]=c) which can also be written foo=([0]=a b c) be-
                 cause indices are incremented automatically.

            -a | -o allexport
                 All new parameters are created with the export attribute.

            -b | -o notify
                 Print job notification messages asynchronously, instead of
                 just before the prompt. Only used if job control is enabled
                 (-m).

            -C | -o noclobber
                 Prevent > redirection from overwriting existing files. In-
                 stead, >| must be used to force an overwrite. Note that this
                 is not safe to use for creation of temporary files or lock-
                 files due to a TOCTOU in a check allowing one to redirect
                 output to /dev/null or other device files even in noclobber
                 mode.

            -e | -o errexit
                 Exit (after executing the ERR trap) as soon as an error oc-
                 curs or a command fails (i.e. exits with a non-zero status).
                 This does not apply to commands whose exit status is expli-
                 citly tested by a shell construct such as if, until, while,
                 or ! statements. For && or ||, only the status of the last
                 command is tested.

            -f | -o noglob
                 Do not expand file name patterns.

            -h | -o trackall
                 Create tracked aliases for all executed commands (see Aliases
                 above). Enabled by default for non-interactive shells.

            -i | -o interactive
                 The shell is an interactive shell. This option can only be
                 used when the shell is invoked. See above for a description
                 of what this means.

            -k | -o keyword
                 Parameter assignments are recognised anywhere in a command.

            -l | -o login
                 The shell is a login shell. This option can only be used when
                 the shell is invoked. See above for a description of what
                 this means.

            -m | -o monitor
                 Enable job control (default for interactive shells).

            -n | -o noexec
                 Do not execute any commands. Useful for checking the syntax
                 of scripts (ignored if interactive).

            -p | -o privileged
                 The shell is a privileged shell. It is set automatically if,
                 when the shell starts, the real UID or GID does not match the
                 effective UID (EUID) or GID (EGID), respectively. See above
                 for a description of what this means.

            -r | -o restricted
                 The shell is a restricted shell. This option can only be used
                 when the shell is invoked. See above for a description of
                 what this means.

            -s | -o stdin
                 If used when the shell is invoked, commands are read from
                 standard input. Set automatically if the shell is invoked
                 with no arguments.

                 When -s is used with the set command it causes the specified
                 arguments to be sorted before assigning them to the position-
                 al parameters (or to array name, if -A is used).

            -U | -o utf8-mode
                 Enable UTF-8 support in the Emacs editing mode and internal
                 string handling functions. This flag is disabled by default,
                 but can be enabled by setting it on the shell command line;
                 is enabled automatically for interactive shells if requested
                 at compile time, your system supports setlocale(LC_CTYPE, "")
                 and optionally nl_langinfo(CODESET), or the LC_ALL, LC_CTYPE,
                 or LANG environment variables, and at least one of these re-
                 turns something that matches "UTF-8" or "utf8" case-
                 insensitively; for direct builtin calls depending on the
                 aforementioned environment variables; or for stdin or
                 scripts, if the input begins with a UTF-8 Byte Order Mark.

            -u | -o nounset
                 Referencing of an unset parameter, other than "$@" or "$*",
                 is treated as an error, unless one of the '-', '+', or '='
                 modifiers is used.

            -v | -o verbose
                 Write shell input to standard error as it is read.

            -X | -o markdirs
                 Mark directories with a trailing '/' during file name genera-
                 tion.

            -x | -o xtrace
                 Print command trees when they are executed, preceded by the
                 value of PS4.

            -o bgnice
                 Background jobs are run with lower priority.

            -o braceexpand
                 Enable brace expansion (a.k.a. alternation). This is enabled
                 by default. If disabled, tilde expansion after an equals sign
                 is disabled as a side effect.

            -o emacs
                 Enable BRL emacs-like command-line editing (interactive
                 shells only); see Emacs editing mode.

            -o gmacs
                 Enable gmacs-like command-line editing (interactive shells
                 only). Currently identical to emacs editing except that
                 transpose-chars (^T) acts slightly differently.

            -o ignoreeof
                 The shell will not (easily) exit when end-of-file is read;
                 exit must be used. To avoid infinite loops, the shell will
                 exit if EOF is read 13 times in a row.

            -o inherit-xtrace
                 Do not reset -o xtrace upon entering functions. This is en-
                 abled by default.

            -o nohup
                 Do not kill running jobs with a SIGHUP signal when a login
                 shell exits. Currently set by default, but this may change in
                 the future to be compatible with AT&T UNIX ksh, which doesn't
                 have this option, but does send the SIGHUP signal.

            -o nolog
                 No effect. In the original Korn shell, this prevents function
                 definitions from being stored in the history file.

            -o physical
                 Causes the cd and pwd commands to use "physical" (i.e. the
                 filesystem's) '..' directories instead of "logical" direc-
                 tories (i.e. the shell handles '..', which allows the user to
                 be oblivious of symbolic links to directories). Clear by de-
                 fault. Note that setting this option does not affect the
                 current value of the PWD parameter; only the cd command
                 changes PWD. See the cd and pwd commands above for more de-
                 tails.

            -o pipefail
                 Make the exit status of a pipeline (before logically comple-
                 menting) the rightmost non-zero errorlevel, or zero if all
                 commands exited with zero.

            -o posix
                 Enable a somewhat more POSIXish mode. As a side effect, set-
                 ting this flag turns off braceexpand mode, which can be
                 turned back on manually, and sh mode.

            -o sh
                 Enable /bin/sh (kludge) mode. Automatically enabled if the
                 basename of the shell invocation begins with "sh" and this
                 autodetection feature is compiled in (not in MirBSD). As a
                 side effect, setting this flag turns off braceexpand mode,
                 which can be turned back on manually, and posix mode.

            -o vi
                 Enable vi(1)-like command-line editing (interactive shells
                 only). See Vi editing mode for documentation and limitations.

            -o vi-esccomplete
                 In vi command-line editing, do command and file name comple-
                 tion when escape (^[) is entered in command mode.

            -o vi-tabcomplete
                 In vi command-line editing, do command and file name comple-
                 tion when tab (^I) is entered in insert mode. This is the de-
                 fault.

            -o viraw
                 No effect. In the original Korn shell, unless viraw was set,
                 the vi command-line mode would let the tty(4) driver do the
                 work until ESC (^[) was entered. mksh is always in viraw
                 mode.

            These options can also be used upon invocation of the shell. The
            current set of options (with single letter names) can be found in
            the parameter '$-'. set -o with no option name will list all the
            options and whether each is on or off; set +o will print the long
            names of all options that are currently on.

            Remaining arguments, if any, are positional parameters and are as-
            signed, in order, to the positional parameters (i.e. $1, $2,
            etc.). If options end with '--' and there are no remaining argu-
            ments, all positional parameters are cleared. If no options or ar-
            guments are given, the values of all names are printed. For unk-
            nown historical reasons, a lone '-' option is treated specially -
            it clears both the -v and -x options.

     shift [number]
            The positional parameters number+1, number+2, etc. are renamed to
            '1', '2', etc. number defaults to 1.

     sleep seconds
            Suspends execution for a minimum of the seconds specified as posi-
            tive decimal value with an optional fractional part. Signal
            delivery may continue execution earlier.

     source file [arg ...]
            Like . ("dot"), except that the current working directory is ap-
            pended to the PATH in GNU bash and mksh. In ksh93 and mksh, this
            is implemented as a shell alias instead of a builtin.

     suspend
            Stops the shell as if it had received the suspend character from
            the terminal. It is not possible to suspend a login shell unless
            the parent process is a member of the same terminal session but is
            a member of a different process group. As a general rule, if the
            shell was started by another shell or via su(1), it can be
            suspended.

     test expression
     [ expression ]
            test evaluates the expression and returns zero status if true, 1
            if false, or greater than 1 if there was an error. It is normally
            used as the condition command of if and while statements. Symbolic
            links are followed for all file expressions except -h and -L.

            The following basic expressions are available:

            -a file
                 file exists.

            -b file
                 file is a block special device.

            -c file
                 file is a character special device.

            -d file
                 file is a directory.

            -e file
                 file exists.

            -f file
                 file is a regular file.

            -G file
                 file's group is the shell's effective group ID.

            -g file
                 file's mode has the setgid bit set.

            -H file
                 file is a context dependent directory (only useful on HP-UX).

            -h file
                 file is a symbolic link.

            -k file
                 file's mode has the sticky(8) bit set.

            -L file
                 file is a symbolic link.

            -O file
                 file's owner is the shell's effective user ID.

            -o option
                 Shell option is set (see the set command above for a list of
                 options). As a non-standard extension, if the option starts
                 with a '!', the test is negated; the test always fails if
                 option doesn't exist (so [ -o foo -o -o !foo ] returns true
                 if and only if option foo exists). The same can be achieved
                 with [ -o ?foo ] like in AT&T UNIX ksh93. option can also be
                 the short flag led by either '-' or '+' (no logical
                 negation), for example '-x' or '+x' instead of 'xtrace'.

            -p file
                 file is a named pipe (FIFO).

            -r file
                 file exists and is readable.

            -S file
                 file is a unix(4)-domain socket.

            -s file
                 file is not empty.

            -t fd
                 File descriptor fd is a tty(4) device.

            -u file
                 file's mode has the setuid bit set.

            -w file
                 file exists and is writable.

            -x file
                 file exists and is executable.

            file1 -nt file2
                 file1 is newer than file2 or file1 exists and file2 does not.

            file1 -ot file2
                 file1 is older than file2 or file2 exists and file1 does not.

            file1 -ef file2
                 file1 is the same file as file2.

            string
                 string has non-zero length.

            -n string
                 string is not empty.

            -z string
                 string is empty.

            string = string
                 Strings are equal.

            string == string
                 Strings are equal.

            string > string
                 First string operand is greater than second string operand.

            string < string
                 First string operand is less than second string operand.

            string != string
                 Strings are not equal.

            number -eq number
                 Numbers compare equal.

            number -ne number
                 Numbers compare not equal.

            number -ge number
                 Numbers compare greater than or equal.

            number -gt number
                 Numbers compare greater than.

            number -le number
                 Numbers compare less than or equal.

            number -lt number
                 Numbers compare less than.

            The above basic expressions, in which unary operators have pre-
            cedence over binary operators, may be combined with the following
            operators (listed in increasing order of precedence):

                  expr -o expr            Logical OR.
                  expr -a expr            Logical AND.
                  ! expr                  Logical NOT.
                  ( expr )                Grouping.

            Note that a number actually may be an arithmetic expression, such
            as a mathematical term or the name of an integer variable:

                  x=1; [ "x" -eq 1 ]      evaluates to true

            Note that some special rules are applied (courtesy of POSIX) if
            the number of arguments to test or inside the brackets [ ... ] is
            less than five: if leading '!' arguments can be stripped such that
            only one to three arguments remain, then the lowered comparison is
            executed; (thanks to XSI) parentheses \( ... \) lower four- and
            three-argument forms to two- and one-argument forms, respectively;
            three-argument forms ultimately prefer binary operations, followed
            by negation and parenthesis lowering; two- and four-argument forms
            prefer negation followed by parenthesis; the one-argument form al-
            ways implies -n.

            Note: A common mistake is to use "if [ $foo = bar ]" which fails
            if parameter "foo" is NULL or unset, if it has embedded spaces
            (i.e. IFS octets), or if it is a unary operator like '!' or '-n'.
            Use tests like "if [ x"$foo" = x"bar" ]" instead, or the double-
            bracket operator "if [[ $foo = bar ]]" or, to avoid pattern match-
            ing (see [[ above): "if [[ $foo = "$bar" ]]"

            The [[ ... ]] construct is not only more secure to use but also
            often faster.

     time [-p] [pipeline]
            If a pipeline is given, the times used to execute the pipeline are
            reported. If no pipeline is given, then the user and system time
            used by the shell itself, and all the commands it has run since it
            was started, are reported. The times reported are the real time
            (elapsed time from start to finish), the user CPU time (time spent
            running in user mode), and the system CPU time (time spent running
            in kernel mode). Times are reported to standard error; the format
            of the output is:

                  0m0.00s real     0m0.00s user     0m0.00s system

            If the -p option is given the output is slightly longer:

                  real     0.00
                  user     0.00
                  sys      0.00

            It is an error to specify the -p option unless pipeline is a sim-
            ple command.

            Simple redirections of standard error do not affect the output of
            the time command:

                  $ time sleep 1 2>afile
                  $ { time sleep 1; } 2>afile

            Times for the first command do not go to "afile", but those of the
            second command do.

     times  Print the accumulated user and system times used both by the shell
            and by processes that the shell started which have exited. The
            format of the output is:

                  0m0.00s 0m0.00s
                  0m0.00s 0m0.00s

     trap [handler signal ...]
            Sets a trap handler that is to be executed when any of the speci-
            fied signals are received. handler is either a NULL string, indi-
            cating the signals are to be ignored, a minus sign ('-'), indicat-
            ing that the default action is to be taken for the signals (see
            signal(3)), or a string containing shell commands to be evaluated
            and executed at the first opportunity (i.e. when the current com-
            mand completes, or before printing the next PS1 prompt) after re-
            ceipt of one of the signals. signal is the name of a signal (e.g.
            PIPE or ALRM) or the number of the signal (see the kill -l command
            above).

            There are two special signals: EXIT (also known as 0) which is ex-
            ecuted when the shell is about to exit, and ERR, which is executed
            after an error occurs (an error is something that would cause the
            shell to exit if the -e or errexit option were set - see the set
            command above). EXIT handlers are executed in the environment of
            the last executed command. Note that for non-interactive shells,
            the trap handler cannot be changed for signals that were ignored
            when the shell started.

            With no arguments, trap lists, as a series of trap commands, the
            current state of the traps that have been set since the shell
            started. Note that the output of trap cannot be usefully piped to
            another process (an artifact of the fact that traps are cleared
            when subprocesses are created).

            The original Korn shell's DEBUG trap and the handling of ERR and
            EXIT traps in functions are not yet implemented.

     true   A command that exits with a zero value.

     global [[+-alpnrtUux] [-L[n]] [-R[n]] [-Z[n]] [-i[n]] | -f [-tux]]
            [name[=value] ...]
     typeset [[+-alpnrtUux] [-LRZ[n]] [-i[n]] | -f [-tux]] [name[=value] ...]
            Display or set parameter attributes. With no name arguments,
            parameter attributes are displayed; if no options are used, the
            current attributes of all parameters are printed as typeset com-
            mands; if an option is given (or '-' with no option letter), all
            parameters and their values with the specified attributes are
            printed; if options are introduced with '+', parameter values are
            not printed.

            If name arguments are given, the attributes of the named parame-
            ters are set (-) or cleared (+). Values for parameters may option-
            ally be specified. For name[*], the change affects the entire ar-
            ray, and no value may be specified.

            If typeset is used inside a function, any parameters specified are
            localised. This is not done by the otherwise identical global.
            Note: This means that mksh's global command is not equivalent to
            other programming languages' as it does not allow a function
            called from another function to access a parameter at truly global
            scope, but only prevents putting an accessed one into local scope.

            When -f is used, typeset operates on the attributes of functions.
            As with parameters, if no name arguments are given, functions are
            listed with their values (i.e. definitions) unless options are in-
            troduced with '+', in which case only the function names are re-
            ported.

            -a      Indexed array attribute.

            -f      Function mode. Display or set functions and their attri-
                    butes, instead of parameters.

            -i[n]   Integer attribute. n specifies the base to use when
                    displaying the integer (if not specified, the base given
                    in the first assignment is used). Parameters with this at-
                    tribute may be assigned values containing arithmetic ex-
                    pressions.

            -L[n]   Left justify attribute. n specifies the field width. If n
                    is not specified, the current width of a parameter (or the
                    width of its first assigned value) is used. Leading whi-
                    tespace (and zeros, if used with the -Z option) is
                    stripped. If necessary, values are either truncated or
                    space padded to fit the field width.

            -l      Lower case attribute. All upper case characters in values
                    are converted to lower case. (In the original Korn shell,
                    this parameter meant "long integer" when used with the -i
                    option.)

            -n      Create a bound variable (name reference): any access to
                    the variable name will access the variable value in the
                    current scope (this is different from AT&T UNIX ksh93!)
                    instead. Also different from AT&T UNIX ksh93 is that value
                    is lazily evaluated at the time name is accessed. This can
                    be used by functions to access variables whose names are
                    passed as parametres, instead of using eval.

            -p      Print complete typeset commands that can be used to re-
                    create the attributes and values of parameters.

            -R[n]   Right justify attribute. n specifies the field width. If n
                    is not specified, the current width of a parameter (or the
                    width of its first assigned value) is used. Trailing whi-
                    tespace is stripped. If necessary, values are either
                    stripped of leading characters or space padded to make
                    them fit the field width.

            -r      Read-only attribute. Parameters with this attribute may
                    not be assigned to or unset. Once this attribute is set,
                    it cannot be turned off.

            -t      Tag attribute. Has no meaning to the shell; provided for
                    application use.

                    For functions, -t is the trace attribute. When functions
                    with the trace attribute are executed, the xtrace (-x)
                    shell option is temporarily turned on.

            -U      Unsigned integer attribute. Integers are printed as un-
                    signed values (combine with the -i option). This option is
                    not in the original Korn shell.

            -u      Upper case attribute. All lower case characters in values
                    are converted to upper case. (In the original Korn shell,
                    this parameter meant "unsigned integer" when used with the
                    -i option which meant upper case letters would never be
                    used for bases greater than 10. See the -U option.)

                    For functions, -u is the undefined attribute. See
                    Functions above for the implications of this.

            -x      Export attribute. Parameters (or functions) are placed in
                    the environment of any executed commands. Exported func-
                    tions are not yet implemented.

            -Z[n]   Zero fill attribute. If not combined with -L, this is the
                    same as -R, except zero padding is used instead of space
                    padding. For integers, the number instead of the base is
                    padded.

            If any of the -i, -L, -l, -R, -U, -u, or -Z options are changed,
            all others from this set are cleared, unless they are also given
            on the same command line.

     ulimit [-aBCcdefHilMmnOPpqrSsTtVvw] [value]
            Display or set process limits. If no options are used, the file
            size limit (-f) is assumed. value, if specified, may be either an
            arithmetic expression or the word "unlimited". The limits affect
            the shell and any processes created by the shell after a limit is
            imposed. Note that some systems may not allow limits to be in-
            creased once they are set. Also note that the types of limits
            available are system dependent - some systems have only the -f
            limit.

            -a     Display all limits; unless -H is used, soft limits are
                   displayed.

            -B n   Set the socket buffer size to n kibibytes.

            -C n   Set the number of cached threads to n.

            -c n   Impose a size limit of n blocks on the size of core dumps.

            -d n   Impose a size limit of n kibibytes on the size of the data
                   area.

            -e n   Set the maximum niceness to n.

            -f n   Impose a size limit of n blocks on files written by the
                   shell and its child processes (files of any size may be
                   read).

            -H     Set the hard limit only (the default is to set both hard
                   and soft limits).

            -i n   Set the number of pending signals to n.

            -l n   Impose a limit of n kibibytes on the amount of locked
                   (wired) physical memory.

            -M n   Set the AIO locked memory to n kibibytes.

            -m n   Impose a limit of n kibibytes on the amount of physical
                   memory used.

            -n n   Impose a limit of n file descriptors that can be open at
                   once.

            -O n   Set the number of AIO operations to n.

            -P n   Limit the number of threads per process to n.

            -p n   Impose a limit of n processes that can be run by the user
                   at any one time.

            -q n   Limit the size of POSIX message queues to n bytes.

            -r n   Set the maximum real-time priority to n.

            -S     Set the soft limit only (the default is to set both hard
                   and soft limits).

            -s n   Impose a size limit of n kibibytes on the size of the stack
                   area.

            -T n   Impose a time limit of n real seconds to be used by each
                   process.

            -t n   Impose a time limit of n CPU seconds spent in user mode to
                   be used by each process.

            -V n   Set the number of vnode monitors on Haiku to n.

            -v n   Impose a limit of n kibibytes on the amount of virtual
                   memory (address space) used.

            -w n   Impose a limit of n kibibytes on the amount of swap space
                   used.

            As far as ulimit is concerned, a block is 512 bytes.

     umask [-S] [mask]
            Display or set the file permission creation mask, or umask (see
            umask(2)). If the -S option is used, the mask displayed or set is
            symbolic; otherwise, it is an octal number.

            Symbolic masks are like those used by chmod(1). When used, they
            describe what permissions may be made available (as opposed to oc-
            tal masks in which a set bit means the corresponding bit is to be
            cleared). For example, "ug=rwx,o=" sets the mask so files will not
            be readable, writable, or executable by "others", and is
            equivalent (on most systems) to the octal mask "007".

     unalias [-adt] [name ...]
            The aliases for the given names are removed. If the -a option is
            used, all aliases are removed. If the -t or -d options are used,
            the indicated operations are carried out on tracked or directory
            aliases, respectively.

     unset [-fv] parameter ...
            Unset the named parameters (-v, the default) or functions (-f).
            With parameter[*], attributes are kept, only values are unset.

            The exit status is non-zero if any of the parameters have the
            read-only attribute set, zero otherwise.

     wait [job ...]
            Wait for the specified job(s) to finish. The exit status of wait
            is that of the last specified job; if the last job is killed by a
            signal, the exit status is 128 + the number of the signal (see
            kill -l exit-status above); if the last specified job can't be
            found (because it never existed, or had already finished), the
            exit status of wait is 127. See Job control below for the format
            of job. wait will return if a signal for which a trap has been set
            is received, or if a SIGHUP, SIGINT, or SIGQUIT signal is re-
            ceived.

            If no jobs are specified, wait waits for all currently running
            jobs (if any) to finish and exits with a zero status. If job moni-
            toring is enabled, the completion status of jobs is printed (this
            is not the case when jobs are explicitly specified).

     whence [-pv] [name ...]
            For each name, the type of command is listed (reserved word,
            built-in, alias, function, tracked alias, or executable). If the
            -p option is used, a path search is performed even if name is a
            reserved word, alias, etc. Without the -v option, whence is simi-
            lar to command -v except that whence will find reserved words and
            won't print aliases as alias commands. With the -v option, whence
            is the same as command -V. Note that for whence, the -p option
            does not affect the search path used, as it does for command. If
            the type of one or more of the names could not be determined, the
            exit status is non-zero.

Job control

     Job control refers to the shell's ability to monitor and control jobs
     which are processes or groups of processes created for commands or pipe-
     lines. At a minimum, the shell keeps track of the status of the back-
     ground (i.e. asynchronous) jobs that currently exist; this information
     can be displayed using the jobs commands. If job control is fully enabled
     (using set -m or set -o monitor), as it is for interactive shells, the
     processes of a job are placed in their own process group. Foreground jobs
     can be stopped by typing the suspend character from the terminal (normal-
     ly ^Z), jobs can be restarted in either the foreground or background us-
     ing the fg and bg commands, and the state of the terminal is saved or re-
     stored when a foreground job is stopped or restarted, respectively.

     Note that only commands that create processes (e.g. asynchronous com-
     mands, subshell commands, and non-built-in, non-function commands) can be
     stopped; commands like read cannot be.

     When a job is created, it is assigned a job number. For interactive
     shells, this number is printed inside "[..]", followed by the process IDs
     of the processes in the job when an asynchronous command is run. A job
     may be referred to in the bg, fg, jobs, kill, and wait commands either by
     the process ID of the last process in the command pipeline (as stored in
     the $! parameter) or by prefixing the job number with a percent sign
     ('%'). Other percent sequences can also be used to refer to jobs:

     %+ | %% | %    The most recently stopped job, or, if there are no stopped
                    jobs, the oldest running job.

     %-             The job that would be the %+ job if the latter did not ex-
                    ist.

     %n             The job with job number n.

     %?string       The job with its command containing the string string (an
                    error occurs if multiple jobs are matched).

     %string        The job with its command starting with the string string
                    (an error occurs if multiple jobs are matched).

     When a job changes state (e.g. a background job finishes or foreground
     job is stopped), the shell prints the following status information:

           [number] flag status command

     where...

     number   is the job number of the job;

     flag     is the '+' or '-' character if the job is the %+ or %- job,
              respectively, or space if it is neither;

     status   indicates the current state of the job and can be:

              Done [number]
                         The job exited. number is the exit status of the job
                         which is omitted if the status is zero.

              Running    The job has neither stopped nor exited (note that
                         running does not necessarily mean consuming CPU time
                         - the process could be blocked waiting for some
                         event).

              Stopped [signal]
                         The job was stopped by the indicated signal (if no
                         signal is given, the job was stopped by SIGTSTP).

              signal-description ["core dumped"]
                         The job was killed by a signal (e.g. memory fault,
                         hangup); use kill -l for a list of signal descrip-
                         tions. The "core dumped" message indicates the pro-
                         cess created a core file.

     command  is the command that created the process. If there are multiple
              processes in the job, each process will have a line showing its
              command and possibly its status, if it is different from the
              status of the previous process.

     When an attempt is made to exit the shell while there are jobs in the
     stopped state, the shell warns the user that there are stopped jobs and
     does not exit. If another attempt is immediately made to exit the shell,
     the stopped jobs are sent a SIGHUP signal and the shell exits. Similarly,
     if the nohup option is not set and there are running jobs when an attempt
     is made to exit a login shell, the shell warns the user and does not
     exit. If another attempt is immediately made to exit the shell, the run-
     ning jobs are sent a SIGHUP signal and the shell exits.

Interactive input line editing

     The shell supports three modes of reading command lines from a tty(4) in
     an interactive session, controlled by the emacs, gmacs, and vi options
     (at most one of these can be set at once). The default is emacs. Editing
     modes can be set explicitly using the set built-in. If none of these op-
     tions are enabled, the shell simply reads lines using the normal tty(4)
     driver. If the emacs or gmacs option is set, the shell allows emacs-like
     editing of the command; similarly, if the vi option is set, the shell al-
     lows vi-like editing of the command. These modes are described in detail
     in the following sections.

     In these editing modes, if a line is longer than the screen width (see
     the COLUMNS parameter), a '>', '+', or '<' character is displayed in the
     last column indicating that there are more characters after, before and
     after, or before the current position, respectively. The line is scrolled
     horizontally as necessary.

     Completed lines are pushed into the history, unless they begin with an
     IFS octet or IFS white space, or are the same as the previous line.

Emacs editing mode

     When the emacs option is set, interactive input line editing is enabled.
     Warning: This mode is slightly different from the emacs mode in the ori-
     ginal Korn shell. In this mode, various editing commands (typically bound
     to one or more control characters) cause immediate actions without wait-
     ing for a newline. Several editing commands are bound to particular con-
     trol characters when the shell is invoked; these bindings can be changed
     using the bind command.

     The following is a list of available editing commands. Each description
     starts with the name of the command, suffixed with a colon; an [n] (if
     the command can be prefixed with a count); and any keys the command is
     bound to by default, written using caret notation e.g. the ASCII ESC
     character is written as ^[. These control sequences are not case sensi-
     tive. A count prefix for a command is entered using the sequence ^[n,
     where n is a sequence of 1 or more digits. Unless otherwise specified, if
     a count is omitted, it defaults to 1.

     Note that editing command names are used only with the bind command.
     Furthermore, many editing commands are useful only on terminals with a
     visible cursor. The default bindings were chosen to resemble correspond-
     ing Emacs key bindings. The user's tty(4) characters (e.g. ERASE) are
     bound to reasonable substitutes and override the default bindings.

     abort: ^C, ^G
             Abort the current command, empty the line buffer and set the exit
             state to interrupted.

     auto-insert: [n]
             Simply causes the character to appear as literal input. Most or-
             dinary characters are bound to this.

     backward-char: [n] ^B, ^XD, ANSI-CurLeft
             Moves the cursor backward n characters.

     backward-word: [n] ^[b, ANSI-Ctrl-CurLeft, ANSI-Alt-CurLeft
             Moves the cursor backward to the beginning of the word; words
             consist of alphanumerics, underscore ('_'), and dollar sign ('$')
             characters.

     beginning-of-history: ^[<
             Moves to the beginning of the history.

     beginning-of-line: ^A, ANSI-Home
             Moves the cursor to the beginning of the edited input line.

     capitalise-word: [n] ^[C, ^[c
             Uppercase the first character in the next n words, leaving the
             cursor past the end of the last word.

     clear-screen: ^[^L
             Prints a compile-time configurable sequence to clear the screen
             and home the cursor, redraws the entire prompt and the currently
             edited input line. The default sequence works for almost all
             standard terminals.

     comment: ^[#
             If the current line does not begin with a comment character, one
             is added at the beginning of the line and the line is entered (as
             if return had been pressed); otherwise, the existing comment
             characters are removed and the cursor is placed at the beginning
             of the line.

     complete: ^[^[
             Automatically completes as much as is unique of the command name
             or the file name containing the cursor. If the entire remaining
             command or file name is unique, a space is printed after its com-
             pletion, unless it is a directory name in which case '/' is ap-
             pended. If there is no command or file name with the current par-
             tial word as its prefix, a bell character is output (usually
             causing a beep to be sounded).

     complete-command: ^X^[
             Automatically completes as much as is unique of the command name
             having the partial word up to the cursor as its prefix, as in the
             complete command above.

     complete-file: ^[^X
             Automatically completes as much as is unique of the file name
             having the partial word up to the cursor as its prefix, as in the
             complete command described above.

     complete-list: ^I, ^[=
             Complete as much as is possible of the current word, and list the
             possible completions for it. If only one completion is possible,
             match as in the complete command above. Note that ^I is usually
             generated by the TAB (tabulator) key.

     delete-char-backward: [n] ERASE, ^?, ^H
             Deletes n characters before the cursor.

     delete-char-forward: [n] ANSI-Del
             Deletes n characters after the cursor.

     delete-word-backward: [n] WERASE, ^[^?, ^[^H, ^[h
             Deletes n words before the cursor.

     delete-word-forward: [n] ^[d
             Deletes characters after the cursor up to the end of n words.

     down-history: [n] ^N, ^XB, ANSI-CurDown
             Scrolls the history buffer forward n lines (later). Each input
             line originally starts just after the last entry in the history
             buffer, so down-history is not useful until either
             search-history, search-history-up or up-history has been per-
             formed.

     downcase-word: [n] ^[L, ^[l
             Lowercases the next n words.

     edit-line: [n] ^Xe
             Edit line n or the current line, if not specified, interactively.
             The actual command executed is fc -e ${VISUAL:-${EDITOR:-vi}} n.

     end-of-history: ^[>
             Moves to the end of the history.

     end-of-line: ^E, ANSI-End
             Moves the cursor to the end of the input line.

     eot: ^_
             Acts as an end-of-file; this is useful because edit-mode input
             disables normal terminal input canonicalization.

     eot-or-delete: [n] ^D
             Acts as eot if alone on a line; otherwise acts as
             delete-char-forward.

     error: (not bound)
             Error (ring the bell).

     exchange-point-and-mark: ^X^X
             Places the cursor where the mark is and sets the mark to where
             the cursor was.

     expand-file: ^[*
             Appends a '*' to the current word and replaces the word with the
             result of performing file globbing on the word. If no files match
             the pattern, the bell is rung.

     forward-char: [n] ^F, ^XC, ANSI-CurRight
             Moves the cursor forward n characters.

     forward-word: [n] ^[f, ANSI-Ctrl-CurRight, ANSI-Alt-CurRight
             Moves the cursor forward to the end of the nth word.

     goto-history: [n] ^[g
             Goes to history number n.

     kill-line: KILL
             Deletes the entire input line.

     kill-region: ^W
             Deletes the input between the cursor and the mark.

     kill-to-eol: [n] ^K
             Deletes the input from the cursor to the end of the line if n is
             not specified; otherwise deletes characters between the cursor
             and column n.

     list: ^[?
             Prints a sorted, columnated list of command names or file names
             (if any) that can complete the partial word containing the cur-
             sor. Directory names have '/' appended to them.

     list-command: ^X?
             Prints a sorted, columnated list of command names (if any) that
             can complete the partial word containing the cursor.

     list-file: ^X^Y
             Prints a sorted, columnated list of file names (if any) that can
             complete the partial word containing the cursor. File type indi-
             cators are appended as described under list above.

     newline: ^J, ^M
             Causes the current input line to be processed by the shell. The
             current cursor position may be anywhere on the line.

     newline-and-next: ^O
             Causes the current input line to be processed by the shell, and
             the next line from history becomes the current line. This is only
             useful after an up-history, search-history or search-history-up.

     no-op: QUIT
             This does nothing.

     prefix-1: ^[
             Introduces a 2-character command sequence.

     prefix-2: ^X, ^[[, ^[O
             Introduces a 2-character command sequence.

     prev-hist-word: [n] ^[., ^[_
             The last word, or, if given, the nth word (zero-based) of the
             previous (on repeated execution, second-last, third-last, etc.)
             command is inserted at the cursor. Use of this editing command
             trashes the mark.

     quote: ^^, ^V
             The following character is taken literally rather than as an
             editing command.

     redraw: ^L
             Reprints the last line of the prompt string and the current input
             line on a new line.

     search-character-backward: [n] ^[^]
             Search backward in the current line for the nth occurrence of the
             next character typed.

     search-character-forward: [n] ^]
             Search forward in the current line for the nth occurrence of the
             next character typed.

     search-history: ^R
             Enter incremental search mode. The internal history list is
             searched backwards for commands matching the input. An initial
             '^' in the search string anchors the search. The escape key will
             leave search mode. Other commands, including sequences of escape
             as prefix-1 followed by a prefix-1 or prefix-2 key will be exe-
             cuted after leaving search mode. The abort (^G) command will re-
             store the input line before search started. Successive
             search-history commands continue searching backward to the next
             previous occurrence of the pattern. The history buffer retains
             only a finite number of lines; the oldest are discarded as neces-
             sary.

     search-history-up: ANSI-PgUp
             Search backwards through the history buffer for commands whose
             beginning match the portion of the input line before the cursor.
             When used on an empty line, this has the same effect as
             up-history.

     search-history-down: ANSI-PgDn
             Search forwards through the history buffer for commands whose be-
             ginning match the portion of the input line before the cursor.
             When used on an empty line, this has the same effect as
             down-history. This is only useful after an up-history,
             search-history or search-history-up.

     set-mark-command: ^[<space>
             Set the mark at the cursor position.

     transpose-chars: ^T
             If at the end of line, or if the gmacs option is set, this ex-
             changes the two previous characters; otherwise, it exchanges the
             previous and current characters and moves the cursor one charac-
             ter to the right.

     up-history: [n] ^P, ^XA, ANSI-CurUp
             Scrolls the history buffer backward n lines (earlier).

     upcase-word: [n] ^[U, ^[u
             Uppercase the next n words.

     version: ^[^V
             Display the version of mksh. The current edit buffer is restored
             as soon as a key is pressed. The restoring keypress is processed,
             unless it is a space.

     yank: ^Y
             Inserts the most recently killed text string at the current cur-
             sor position.

     yank-pop: ^[y
             Immediately after a yank, replaces the inserted text string with
             the next previously killed text string.

Vi editing mode

     Note: The vi command-line editing mode is orphaned, yet still functional.
     It is 8-bit clean but specifically does not support UTF-8 or MBCS.

     The vi command-line editor in mksh has basically the same commands as the
     vi(1) editor with the following exceptions:

     •   You start out in insert mode.

     •   There are file name and command completion commands: =, \, *, ^X, ^E,
         ^F, and, optionally, <tab> and <esc>.

     •   The _ command is different (in mksh, it is the last argument command;
         in vi(1) it goes to the start of the current line).

     •   The / and G commands move in the opposite direction to the j command.

     •   Commands which don't make sense in a single line editor are not
         available (e.g. screen movement commands and ex(1)-style colon (:)
         commands).

     Like vi(1), there are two modes: "insert" mode and "command" mode. In in-
     sert mode, most characters are simply put in the buffer at the current
     cursor position as they are typed; however, some characters are treated
     specially. In particular, the following characters are taken from current
     tty(4) settings (see stty(1)) and have their usual meaning (normal values
     are in parentheses): kill (^U), erase (^?), werase (^W), eof (^D), intr
     (^C), and quit (^\). In addition to the above, the following characters
     are also treated specially in insert mode:

     ^E       Command and file name enumeration (see below).

     ^F       Command and file name completion (see below). If used twice in a
              row, the list of possible completions is displayed; if used a
              third time, the completion is undone.

     ^H       Erases previous character.

     ^J | ^M  End of line. The current line is read, parsed, and executed by
              the shell.

     ^V       Literal next. The next character typed is not treated specially
              (can be used to insert the characters being described here).

     ^X       Command and file name expansion (see below).

     <esc>    Puts the editor in command mode (see below).

     <tab>    Optional file name and command completion (see ^F above), en-
              abled with set -o vi-tabcomplete.

     In command mode, each character is interpreted as a command. Characters
     that don't correspond to commands, are illegal combinations of commands,
     or are commands that can't be carried out, all cause beeps. In the fol-
     lowing command descriptions, an [n] indicates the command may be prefixed
     by a number (e.g. 10l moves right 10 characters); if no number prefix is
     used, n is assumed to be 1 unless otherwise specified. The term "current
     position" refers to the position between the cursor and the character
     preceding the cursor. A "word" is a sequence of letters, digits, and un-
     derscore characters or a sequence of non-letter, non-digit, non-
     underscore, and non-whitespace characters (e.g. "ab2*&^" contains two
     words) and a "big-word" is a sequence of non-whitespace characters.

     Special mksh vi commands:

     The following commands are not in, or are different from, the normal vi
     file editor:

     [n]_
          Insert a space followed by the nth big-word from the last command in
          the history at the current position and enter insert mode; if n is
          not specified, the last word is inserted.

     #    Insert the comment character ('#') at the start of the current line
          and return the line to the shell (equivalent to I#^J).

     [n]g
          Like G, except if n is not specified, it goes to the most recent
          remembered line.

     [n]v
          Edit line n using the vi(1) editor; if n is not specified, the
          current line is edited. The actual command executed is fc -e
          ${VISUAL:-${EDITOR:-vi}} n.

     * and ^X
          Command or file name expansion is applied to the current big-word
          (with an appended '*' if the word contains no file globbing charac-
          ters) - the big-word is replaced with the resulting words. If the
          current big-word is the first on the line or follows one of the
          characters ';', '|', '&', '(', or ')', and does not contain a slash
          ('/'), then command expansion is done; otherwise file name expansion
          is done. Command expansion will match the big-word against all
          aliases, functions, and built-in commands as well as any executable
          files found by searching the directories in the PATH parameter. File
          name expansion matches the big-word against the files in the current
          directory. After expansion, the cursor is placed just past the last
          word and the editor is in insert mode.

     [n]\, [n]^F, [n]<tab>, and [n]<esc>
          Command/file name completion. Replace the current big-word with the
          longest unique match obtained after performing command and file name
          expansion. <tab> is only recognised if the vi-tabcomplete option is
          set, while <esc> is only recognised if the vi-esccomplete option is
          set (see set -o). If n is specified, the nth possible completion is
          selected (as reported by the command/file name enumeration command).

     = and ^E
          Command/file name enumeration. List all the commands or files that
          match the current big-word.

     ^V   Display the version of mksh. The current edit buffer is restored as
          soon as a key is pressed. The restoring keypress is ignored.

     @c   Macro expansion. Execute the commands found in the alias c.

     Intra-line movement commands:

     [n]h and [n]^H
             Move left n characters.

     [n]l and [n]<space>
             Move right n characters.

     0       Move to column 0.

     ^       Move to the first non-whitespace character.

     [n]|    Move to column n.

     $       Move to the last character.

     [n]b    Move back n words.

     [n]B    Move back n big-words.

     [n]e    Move forward to the end of the word, n times.

     [n]E    Move forward to the end of the big-word, n times.

     [n]w    Move forward n words.

     [n]W    Move forward n big-words.

     %       Find match. The editor looks forward for the nearest parenthesis,
             bracket, or brace and then moves the cursor to the matching
             parenthesis, bracket, or brace.

     [n]fc   Move forward to the nth occurrence of the character c.

     [n]Fc   Move backward to the nth occurrence of the character c.

     [n]tc   Move forward to just before the nth occurrence of the character
             c.

     [n]Tc   Move backward to just before the nth occurrence of the character
             c.

     [n];    Repeats the last f, F, t, or T command.

     [n],    Repeats the last f, F, t, or T command, but moves in the opposite
             direction.

     Inter-line movement commands:

     [n]j, [n]+, and [n]^N
             Move to the nth next line in the history.

     [n]k, [n]-, and [n]^P
             Move to the nth previous line in the history.

     [n]G    Move to line n in the history; if n is not specified, the number
             of the first remembered line is used.

     [n]g    Like G, except if n is not specified, it goes to the most recent
             remembered line.

     [n]/string
             Search backward through the history for the nth line containing
             string; if string starts with '^', the remainder of the string
             must appear at the start of the history line for it to match.

     [n]?string
             Same as /, except it searches forward through the history.

     [n]n    Search for the nth occurrence of the last search string; the
             direction of the search is the same as the last search.

     [n]N    Search for the nth occurrence of the last search string; the
             direction of the search is the opposite of the last search.

     ANSI-CurUp
             Take the characters from the beginning of the line to the current
             cursor position as search string and do a backwards history
             search for lines beginning with this string; keep the cursor po-
             sition. This works only in insert mode and keeps it enabled.

     Edit commands

     [n]a    Append text n times; goes into insert mode just after the current
             position. The append is only replicated if command mode is re-
             entered i.e. <esc> is used.

     [n]A    Same as a, except it appends at the end of the line.

     [n]i    Insert text n times; goes into insert mode at the current posi-
             tion. The insertion is only replicated if command mode is re-
             entered i.e. <esc> is used.

     [n]I    Same as i, except the insertion is done just before the first
             non-blank character.

     [n]s    Substitute the next n characters (i.e. delete the characters and
             go into insert mode).

     S       Substitute whole line. All characters from the first non-blank
             character to the end of the line are deleted and insert mode is
             entered.

     [n]cmove-cmd
             Change from the current position to the position resulting from n
             move-cmds (i.e. delete the indicated region and go into insert
             mode); if move-cmd is c, the line starting from the first non-
             blank character is changed.

     C       Change from the current position to the end of the line (i.e.
             delete to the end of the line and go into insert mode).

     [n]x    Delete the next n characters.

     [n]X    Delete the previous n characters.

     D       Delete to the end of the line.

     [n]dmove-cmd
             Delete from the current position to the position resulting from n
             move-cmds; move-cmd is a movement command (see above) or d, in
             which case the current line is deleted.

     [n]rc   Replace the next n characters with the character c.

     [n]R    Replace. Enter insert mode but overwrite existing characters in-
             stead of inserting before existing characters. The replacement is
             repeated n times.

     [n]~    Change the case of the next n characters.

     [n]ymove-cmd
             Yank from the current position to the position resulting from n
             move-cmds into the yank buffer; if move-cmd is y, the whole line
             is yanked.

     Y       Yank from the current position to the end of the line.

     [n]p    Paste the contents of the yank buffer just after the current po-
             sition, n times.

     [n]P    Same as p, except the buffer is pasted at the current position.

     Miscellaneous vi commands

     ^J and ^M
             The current line is read, parsed, and executed by the shell.

     ^L and ^R
             Redraw the current line.

     [n].    Redo the last edit command n times.

     u       Undo the last edit command.

     U       Undo all changes that have been made to the current line.

     intr and quit
             The interrupt and quit terminal characters cause the current line
             to be deleted and a new prompt to be printed.

FILES

     ~/.mkshrc          User mkshrc profile (non-privileged interactive
                        shells); see Startup files. The location can be
                        changed at compile time (for embedded systems); AOSP
                        Android builds use /system/etc/mkshrc.
     ~/.profile         User profile (non-privileged login shells); see
                        Startup files near the top of this manual.
     /etc/profile       System profile (login shells); see Startup files.
     /etc/shells        Shell database.
     /etc/suid_profile  Suid profile (privileged shells); see Startup files.

     Note: On Android, /system/etc/ contains the system and suid profile.

SEE ALSO

     awk(1), cat(1), ed(1), getopt(1), sed(1), sh(1), stty(1), dup(2),
     execve(2), getgid(2), getuid(2), mknod(2), mkfifo(2), open(2), pipe(2),
     rename(2), wait(2), getopt(3), nl_langinfo(3), setlocale(3), signal(3),
     system(3), tty(4), shells(5), environ(7), script(7), utf-8(7), mknod(8)

     http://docsrv.sco.com:507/en/man/html.C/sh.C.html

     https://www.mirbsd.org/ksh-chan.htm

     Morris Bolsky, The KornShell Command and Programming Language, Prentice
     Hall PTR, xvi + 356 pages, 1989, ISBN 978-0-13-516972-8 (0-13-516972-0).

     Morris I. Bolsky and David G. Korn, The New KornShell Command and
     Programming Language (2nd Edition), Prentice Hall PTR, xvi + 400 pages,
     1995, ISBN 978-0-13-182700-4 (0-13-182700-6).

     Stephen G. Kochan and Patrick H. Wood, UNIX Shell Programming, Sams, 3rd
     Edition, xiii + 437 pages, 2003, ISBN 978-0-672-32490-1 (0-672-32490-3).

     IEEE Inc., IEEE Standard for Information Technology - Portable Operating
     System Interface (POSIX), IEEE Press, Part 2: Shell and Utilities,
     xvii + 1195 pages, 1993, ISBN 978-1-55937-255-8 (1-55937-255-9).

     Bill Rosenblatt, Learning the Korn Shell, O'Reilly, 360 pages, 1993, ISBN
     978-1-56592-054-5 (1-56592-054-6).

     Bill Rosenblatt and Arnold Robbins, Learning the Korn Shell, Second
     Edition, O'Reilly, 432 pages, 2002, ISBN 978-0-596-00195-7
     (0-596-00195-9).

     Barry Rosenberg, KornShell Programming Tutorial, Addison-Wesley
     Professional, xxi + 324 pages, 1991, ISBN 978-0-201-56324-5
     (0-201-56324-X).

AUTHORS

     The MirBSD Korn Shell is developed by Thorsten Glaser <tg@mirbsd.org> and
     currently maintained as part of The MirOS Project. This shell is based on
     the public domain 7th edition Bourne shell clone by Charles Forsyth, who
     kindly agreed to, in countries where the Public Domain status of the work
     may not be valid, grant a copyright licence to the general public to deal
     in the work without restriction and permission to sublicence derivates
     under the terms of any (OSI approved) Open Source licence, and parts of
     the BRL shell by Doug A. Gwyn, Doug Kingston, Ron Natalie, Arnold
     Robbins, Lou Salkind, and others. The first release of pdksh was created
     by Eric Gisin, and it was subsequently maintained by John R. MacMillan
     <change!john@sq.sq.com>, Simon J. Gerraty <sjg@zen.void.oz.au>, and
     Michael Rendell <michael@cs.mun.ca>. The effort of several projects, such
     as Debian and OpenBSD, and other contributors including our users, to im-
     prove the shell is appreciated. See the documentation, CVS, and web site
     for details.

     The BSD daemon is Copyright (C) Marshall Kirk McKusick. The complete
     legalese is at: https://www.mirbsd.org/TaC-mksh.txt

CAVEATS

     mksh only supports the Unicode BMP (Basic Multilingual Plane).

     mksh has a different scope model from AT&T UNIX ksh, which leads to sub-
     tile differences in semantics for identical builtins. This can cause is-
     sues with a nameref to suddenly point to a local variable by accident;
     fixing this is hard.

     The parts of a pipeline, like below, are executed in subshells. Thus,
     variable assignments inside them are not visible in the surrounding exe-
     cution environment. Use co-processes instead.

           foo | bar | read baz            # will not change $baz
           foo | bar |& read -p baz        # will, however, do so

     mksh provides a consistent set of 32-bit integer arithmetics, both signed
     and unsigned, with defined wraparound and sign of the result of a modulo
     operation, even (defying POSIX) on 64-bit systems. If you require 64-bit
     integer arithmetics, use lksh (legacy mksh) instead, but be aware that,
     in POSIX, it's legal for the OS to make print $((2147483647 + 1)) delete
     all files on your system, as it's Undefined Behaviour.

BUGS

     Suspending (using ^Z) pipelines like the one below will only suspend the
     currently running part of the pipeline; in this example, "fubar" is im-
     mediately printed on suspension (but not later after an fg).

           $ /bin/sleep 666 && echo fubar

     This document attempts to describe mksh R50 and up, compiled without any
     options impacting functionality, such as MKSH_SMALL, when not called as
     /bin/sh which, on some systems only, enables set -o sh automatically
     (whose behaviour differs across targets), for an operating environment
     supporting all of its advanced needs. Please report bugs in mksh to the
     MirOS mailing list at <miros-mksh@mirbsd.org> or in the #!/bin/mksh (or
     #ksh) IRC channel at irc.freenode.net (Port 6697 SSL, 6667 unencrypted),
     or at: https://launchpad.net/mksh

MirOS                            July 3, 2014                               50

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These manual pages and other documentation are copyrighted by their respective writers; their source is available at our CVSweb, AnonCVS, and other mirrors. The rest is Copyright © 2002‒2014 The MirOS Project, Germany.
This product includes material provided by Thorsten Glaser.

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