MirOS Manual: psed(1), s2p(1)


S2P(1)          Perl Programmers Reference Guide           S2P(1)

NAME

     psed - a stream editor

SYNOPSIS

        psed [-an] script [file ...]
        psed [-an] [-e script] [-f script-file] [file ...]

        s2p  [-an] [-e script] [-f script-file]

DESCRIPTION

     A stream editor reads the input stream consisting of the
     specified files (or standard input, if none are given),
     processes is line by line by applying a script consisting of
     edit commands, and writes resulting lines to standard out-
     put. The filename `"-"' may be used to read standard input.

     The edit script is composed from arguments of -e options and
     script-files, in the given order. A single script argument
     may be specified as the first parameter.

     If this program is invoked with the name s2p, it will act as
     a sed-to-Perl translator. See "sed Script Translation".

     sed returns an exit code of 0 on success or >0 if an error
     occurred.

OPTIONS

     -a  A file specified as argument to the w edit command is by
         default opened before input processing starts. Using -a,
         opening of such files is delayed until the first line is
         actually written to the file.

     -e script
         The editing commands defined by script are appended to
         the script. Multiple commands must be separated by new-
         lines.

     -f script-file
         Editing commands from the specified script-file are read
         and appended to the script.

     -n  By default, a line is written to standard output after
         the editing script has been applied to it. The -n option
         suppresses automatic printing.

COMMANDS

     sed command syntax is defined as

        [address[,address]][!]function[argument]

     with whitespace being permitted before or after addresses,
     and between the function character and the argument. The

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     addresses and the address inverter ("!") are used to res-
     trict the application of a command to the selected line(s)
     of input.

     Each command must be on a line of its own, except where
     noted in the synopses below.

     The edit cycle performed on each input line consist of read-
     ing the line (without its trailing newline character) into
     the pattern space, applying the applicable commands of the
     edit script, writing the final contents of the pattern space
     and a newline to the standard output. A hold space is pro-
     vided for saving the contents of the pattern space for later
     use.

     Addresses

     A sed address is either a line number or a pattern, which
     may be combined arbitrarily to construct ranges. Lines are
     numbered across all input files.

     Any address may be followed by an exclamation mark (`"!"'),
     selecting all lines not matching that address.

     number
         The line with the given number is selected.

     $   A dollar sign ("$") is the line number of the last line
         of the input stream.

     /regular expression/
         A pattern address is a basic regular expression (see
         "Basic Regular Expressions"), between the delimiting
         character "/". Any other character except "\" or newline
         may be used to delimit a pattern address when the ini-
         tial delimiter is prefixed with a backslash (`"\"').

     If no address is given, the command selects every line.

     If one address is given, it selects the line (or lines)
     matching the address.

     Two addresses select a range that begins whenever the first
     address matches, and ends (including that line) when the
     second address matches. If the first (second) address is a
     matching pattern, the second address is not applied to the
     very same line to determine the end of the range. Likewise,
     if the second address is a matching pattern, the first
     address is not applied to the very same line to determine
     the begin of another range. If both addresses are line
     numbers, and the second line number is less than the first
     line number, then only the first line is selected.

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     Functions

     The maximum permitted number of addresses is indicated with
     each function synopsis below.

     The argument text consists of one or more lines following
     the command. Embedded newlines in text must be preceded with
     a backslash.  Other backslashes in text are deleted and the
     following character is taken literally.

     [1addr]a\ text
         Write text (which must start on the line following the
         command) to standard output immediately before reading
         the next line of input, either by executing the N func-
         tion or by beginning a new cycle.

     [2addr]b [label]
         Branch to the : function with the specified label. If no
         label is given, branch to the end of the script.

     [2addr]c\ text
         The line, or range of lines, selected by the address is
         deleted. The text (which must start on the line follow-
         ing the command) is written to standard output. With an
         address range, this occurs at the end of the range.

     [2addr]d
         Deletes the pattern space and starts the next cycle.

     [2addr]D
         Deletes the pattern space through the first embedded
         newline or to the end. If the pattern space becomes
         empty, a new cycle is started, otherwise execution of
         the script is restarted.

     [2addr]g
         Replace the contents of the pattern space with the hold
         space.

     [2addr]G
         Append a newline and the contents of the hold space to
         the pattern space.

     [2addr]h
         Replace the contents of the hold space with the pattern
         space.

     [2addr]H
         Append a newline and the contents of the pattern space
         to the hold space.

     [1addr]i\ text

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         Write the text (which must start on the line following
         the command) to standard output.

     [2addr]l
         Print the contents of the pattern space: non-printable
         characters are shown in C-style escaped form; long lines
         are split and have a trailing `"\"' at the point of the
         split; the true end of a line is marked with a `"$"'.
         Escapes are: `\a', `\t', `\n', `\f', `\r', `\e' for BEL,
         HT, LF, FF, CR, ESC, respectively, and `\' followed by a
         three-digit octal number for all other non-printable
         characters.

     [2addr]n
         If automatic printing is enabled, write the pattern
         space to the standard output. Replace the pattern space
         with the next line of input. If there is no more input,
         processing is terminated.

     [2addr]N
         Append a newline and the next line of input to the pat-
         tern space. If there is no more input, processing is
         terminated.

     [2addr]p
         Print the pattern space to the standard output. (Use the
         -n option to suppress automatic printing at the end of a
         cycle if you want to avoid double printing of lines.)

     [2addr]P
         Prints the pattern space through the first embedded new-
         line or to the end.

     [1addr]q
         Branch to the end of the script and quit without start-
         ing a new cycle.

     [1addr]r file
         Copy the contents of the file to standard output immedi-
         ately before the next attempt to read a line of input.
         Any error encountered while reading file is silently
         ignored.

     [2addr]s/regular expression/replacement/flags
         Substitute the replacement string for the first sub-
         string in the pattern space that matches the regular
         expression. Any character other than backslash or new-
         line can be used instead of a slash to delimit the regu-
         lar expression and the replacement. To use the delimiter
         as a literal character within the regular expression and
         the replacement, precede the character by a backslash
         (`"\"').

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         Literal newlines may be embedded in the replacement
         string by preceding a newline with a backslash.

         Within the replacement, an ampersand (`"&"') is replaced
         by the string matching the regular expression. The
         strings `"\1"' through `"\9"' are replaced by the
         corresponding subpattern (see "Basic Regular Expres-
         sions"). To get a literal `"&"' or `"\"' in the replace-
         ment text, precede it by a backslash.

         The following flags modify the behaviour of the s com-
         mand:

         g       The replacement is performed for all matching,
                 non-overlapping substrings of the pattern space.

         1..9    Replace only the n-th matching substring of the
                 pattern space.

         p       If the substitution was made, print the new
                 value of the pattern space.

         w file  If the substitution was made, write the new
                 value of the pattern space to the specified
                 file.

     [2addr]t [label]
         Branch to the : function with the specified label if any
         s substitutions have been made since the most recent
         reading of an input line or execution of a t function.
         If no label is given, branch to the end of the script.

     [2addr]w file
         The contents of the pattern space are written to the
         file.

     [2addr]x
         Swap the contents of the pattern space and the hold
         space.

     [1addr]=
         Prints the current line number on the standard output.

     [0addr]: [label]
         The command specifies the position of the label. It has
         no other effect.

     [2addr]{ [command]
     [0addr]}
         These two commands begin and end a command list. The
         first command may be given on the same line as the open-
         ing { command. The commands within the list are jointly

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         selected by the address(es) given on the { command (but
         may still have individual addresses).

     [0addr]# [comment]
         The entire line is ignored (treated as a comment). If,
         however, the first two characters in the script are
         `"#n"', automatic printing of output is suppressed, as
         if the -n option were given on the command line.

BASIC REGULAR EXPRESSIONS

     A Basic Regular Expression (BRE), as defined in POSIX
     1003.2, consists of atoms, for matching parts of a string,
     and bounds, specifying repetitions of a preceding atom.

     Atoms

     The possible atoms of a BRE are: ., matching any single
     character; ^ and $, matching the null string at the begin-
     ning or end of a string, respectively; a bracket expres-
     sions, enclosed in [ and ] (see below); and any single char-
     acter with no other significance (matching that character).
     A \ before one of: ., ^, $, [, *, \, matching the character
     after the backslash. A sequence of atoms enclosed in \( and
     \) becomes an atom and establishes the target for a
     backreference, consisting of the substring that actually
     matches the enclosed atoms. Finally, \ followed by one of
     the digits 0 through 9 is a backreference.

     A ^ that is not first, or a $ that is not last does not have
     a special significance and need not be preceded by a
     backslash to become literal. The same is true for a ], that
     does not terminate a bracket expression.

     An unescaped backslash cannot be last in a BRE.

     Bounds

     The BRE bounds are: *, specifying 0 or more matches of the
     preceding atom; \{count\}, specifying that many repetitions;
     \{minimum,\}, giving a lower limit; and \{minimum,maximum\}
     finally defines a lower and upper bound.

     A bound appearing as the first item in a BRE is taken
     literally.

     Bracket Expressions

     A bracket expression is a list of characters, character
     ranges and character classes enclosed in [ and ] and matches
     any single character from the represented set of characters.

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     A character range is written as two characters separated by
     - and represents all characters (according to the character
     collating sequence) that are not less than the first and not
     greater than the second. (Ranges are very
     collating-sequence-dependent, and portable programs should
     avoid relying on them.)

     A character class is one of the class names

        alnum     digit     punct
        alpha     graph     space
        blank     lower     upper
        cntrl     print     xdigit

     enclosed in [: and :] and represents the set of characters
     as defined in ctype(3).

     If the first character after [ is ^, the sense of matching
     is inverted.

     To include a literal `"^"', place it anywhere else but
     first. To include a literal '"]"' place it first or immedi-
     ately after an initial ^. To include a literal `"-"' make it
     the first (or second after ^) or last character, or the
     second endpoint of a range.

     The special bracket expression constructs "[[:<:]]" and
     "[[:>:]]" match the null string at the beginning and end of
     a word respectively. (Note that neither is identical to
     Perl's `\b' atom.)

     Additional Atoms

     Since some sed implementations provide additional regular
     expression atoms (not defined in POSIX 1003.2), psed is
     capable of translating the following backslash escapes:

     \< This is the same as "[[:>:]]".
     \> This is the same as "[[:<:]]".
     \w This is an abbreviation for "[[:alnum:]_]".
     \W This is an abbreviation for "[^[:alnum:]_]".
     \y Match the empty string at a word boundary.
     \B Match the empty string between any two either word or non-
      word characters.

     To enable this feature, the environment variable PSEDEXTBRE
     must be set to a string containing the requested characters,
     e.g.: "PSEDEXTBRE='<>wW'".

ENVIRONMENT

     The environment variable "PSEDEXTBRE" may be set to extend
     BREs. See "Additional Atoms".

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DIAGNOSTICS

     ambiguous translation for character `%s' in `y' command
         The indicated character appears twice, with different
         translations.

     `[' cannot be last in pattern
         A `[' in a BRE indicates the beginning of a bracket
         expression.

     `\' cannot be last in pattern
         A `\' in a BRE is used to make the subsequent character
         literal.

     `\' cannot be last in substitution
         A `\' in a subsitution string is used to make the subse-
         quent character literal.

     conflicting flags `%s'
         In an s command, either the `g' flag and an n-th
         occurrence flag, or multiple n-th occurrence flags are
         specified. Note that only the digits `1' through `9' are
         permitted.

     duplicate label %s (first defined at %s)
     excess address(es)
         The command has more than the permitted number of
         addresses.

     extra characters after command (%s)
     illegal option `%s'
     improper delimiter in s command
         The BRE and substitution may not be delimited with `\'
         or newline.

     invalid address after `,'
     invalid backreference (%s)
         The specified backreference number exceeds the number of
         backreferences in the BRE.

     invalid repeat clause `\{%s\}'
         The repeat clause does not contain a valid integer
         value, or pair of values.

     malformed regex, 1st address
     malformed regex, 2nd address
     malformed regular expression
     malformed substitution expression
     malformed `y' command argument
         The first or second string of a y command  is syntacti-
         cally incorrect.

     maximum less than minimum in `\{%s\}'

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     no script command given
         There must be at least one -e or one -f option specify-
         ing a script or script file.

     `\' not valid as delimiter in `y' command
     option -e requires an argument
     option -f requires an argument
     `s' command requires argument
     start of unterminated `{'
     string lengths in `y' command differ
         The translation table strings in a y commanf must have
         equal lengths.

     undefined label `%s'
     unexpected `}'
         A } command without a preceding { command was encoun-
         tered.

     unexpected end of script
         The end of the script was reached although a text line
         after a a, c or i command indicated another line.

     unknown command `%s'
     unterminated `['
         A BRE contains an unterminated bracket expression.

     unterminated `\('
         A BRE contains an unterminated backreference.

     `\{' without closing `\}'
         A BRE contains an unterminated bounds specification.

     `\)' without preceding `\('
     `y' command requires argument

EXAMPLE

     The basic material for the preceding section was generated
     by running the sed script

        #no autoprint
        s/^.*Warn( *"\([^"]*\)".*$/\1/
        t process
        b
        :process
        s/$!/%s/g
        s/$[_[:alnum:]]\{1,\}/%s/g
        s/\\\\/\\/g
        s/^/=item /
        p

     on the program's own text, and piping the output into "sort
     -u".

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SED SCRIPT TRANSLATION

     If this program is invoked with the name s2p it will act as
     a sed-to-Perl translator. After option processing (all other
     arguments are ignored), a Perl program is printed on stan-
     dard output, which will process the input stream (as read
     from all arguments) in the way defined by the sed script and
     the option setting used for the translation.

SEE ALSO

     perl(1), re_format(7)

BUGS

     The l command will show escape characters (ESC) as `"\e"',
     but a vertical tab (VT) in octal.

     Trailing spaces are truncated from labels in :, t and b com-
     mands.

     The meaning of an empty regular expression (`"//"'), as
     defined by sed, is "the last pattern used, at run time".
     This deviates from the Perl interpretation, which will re-
     use the "last last successfully executed regular expres-
     sion". Since keeping track of pattern usage would create
     terribly cluttered code, and differences would only appear
     in obscure context (where other sed implementations appear
     to deviate, too), the Perl semantics was adopted. Note that
     common usage of this feature, such as in "/abc/s//xyz/",
     will work as expected.

     Collating elements (of bracket expressions in BREs) are not
     implemented.

STANDARDS

     This sed implementation conforms to the IEEE Std1003.2-1992
     ("POSIX.2") definition of sed, and is compatible with the
     OpenBSD implementation, except where otherwise noted (see
     "BUGS").

AUTHOR

     This Perl implementation of sed was written by Wolfgang
     Laun, Wolfgang.Laun@alcatel.at.

COPYRIGHT and LICENSE

     This program is free and open software. You may use, modify,
     distribute, and sell this program (and any modified vari-
     ants) in any way you wish, provided you do not restrict oth-
     ers from doing the same.

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