mksh(1) R35b

This is the website of the MirBSD™ Korn Shell, an actively developed free implementation of the Korn Shell programming language and a successor to the Public Domain Korn Shell (pdksh).

This page is always accessible via a redirection at http://mirbsd.de/mksh, which is the canonical homepage URI, and in case the webserver is unreachable, the backup page will provide basic information. The FSF/UNESCO directory of Free Software lists mksh, too.

Table of Contents

Introduction

The current version of mksh is mksh R35b from 18 July 2008.

Thanks to “Der Verein trash.net” for sponsoring access to a Solaris 8 box. Thanks to HP TestDrive, which helps in keeping mksh portable to several Unixes and compilers, and track down some architecture- or glibc-specific bugs. Thanks to Julian “yofuh” Wiesener for just another account on a Sun E420 on Solaris 11β. Thanks to someone who prefers to stay anonymous due to tons of red tape for providing access to an AIX 5.3 system with gcc and xlC installed. Thanks to gnubber’s admin (Barry “bddebian” deFreese), as well as Samuel “youpi” Thibault, for providing shell access to a Debian GNU/HURD system. Thanks to Lucas “laffer1” Holt for ssh access to the MidnightBSD server. Thanks to Waldemar “wbx” Brodkorb for dropping his unused Zaurus SL-C3200 to someone who can actually make use of it to test mksh on OpenBSD. Thanks to Andreas “gecko2” Gockel for access to a couple of Debian and Macintosh boxen. Thanks to Martin Zobel-Helas for an account on an Alpha system. Thanks to Bastian “waldi” Blank for access to an S/390 system and uploading mksh packages to Debian for quite some time. Also thanks to Otavio Salvador for uploading a couple of my Debian packages. The Debian GNU/k*BSD and HURD developers were quite helpful in assisting and testing as well. Thanks to Thomas E. “TGEN” Spanjaard for access to both a NetBSD and a DragonFly system. Thanks to Josef “jupp” / “penpen” Schugt for testing mksh on a Digital Unix (OSF/1 V4.0) system from the Uni Bonn Physik CIP Pool. Thanks to DEChengst from #UnixNL for providing access to a HP/Compaq Tru64 (OSF/1 V5.1B) system, an OSF/1 V2.0 system and an Ultrix 4.5 system. Thanks to Adam “replaced” Hoka for a BSDi BSD/OS 3.1 ISO9660 image. (Did I miss anyone? Mail me if so.)

What is mksh(1)? – Short answer: The MirBSD Korn Shell. Okay, but what exactly does it do, or why another shell? These questions will be answered below for the people interested. Right now, you only need to know that mksh is a DFSG-free and OSD-compliant successor to pdksh, developed as part of the MirOS Project as native bourne/POSIX/korn shell for MirOS BSD, but also to be readily available under other UNIX®-like operating systems.

The source code for mksh is available at the MirOS Project mirrors as well as these of other operating system projects due to being included in these; however, we do not provide binaries. Find instructions to build and install mksh below, or ask your operating environment vendor to package and include mksh; we provide assistance for this task if asked. Licencing permits this as long as due credit is given to the authors and contributors and the copyright notices are not removed in their entirety; modifying is allowed (but if the result is still called mksh, it’s discouraged; talk with us if you feel you have to modify mksh). The individual licences used are the MirOS licence, 2-clause and 3-clause UCB licences and the ISC licence; full terms are available via CVSweb. pdksh originally was public domain, with a few exceptions, but these files are not part of mksh R21 or up. The mksh(1) author (mirabilos) acknowledges the contributions of these people who dedicated pdksh to the public, and asserts a collective copyright on the code. All these licences are DFSG clean and conform to the OSD, and the MirOS Licence is listed on the pages of the ifrOSS licence centre as well as in the FSF/UNESCO Directory of Free Software.

To compile mksh, you will need a bourne or POSIX shell (Solaris /bin/sh is enough, and the Z shell should work), a C compiler (at the moment, only the one from the GNU Compiler Collection works, but we’re attempting to change this), system and C library header files and the standard C runtime. You will also need a set of standard UNIX® tools on a supported operating system: any recent BSD; Darwin, Apple Mac OSX; Interix (Microsoft® Services for Unix 3.5, maybe Subsystem for Unix Applications); GNU/Cygwin; UWIN; GNU/Linux (libc5, glibc, and uClibc systems are tested), Debian GNU/kFreeBSD, GNU/HURD or GNU/Linux; Sun Solaris (8, 9, 10, 11), OpenSolaris; AIX; HP-UX 11i; OSF/1; ULTRIX
To run the regression test suite, you will need a not too antiquated Perl with POSIX.pm as well as /bin/ed (whose installation is strongly suggested anyway, because it’s the standard FCEDIT history editor and standard UNIX® text editor), as well as a controlling terminal, usually /dev/tty or provided from script(1) or GNU screen.

To use mksh, you only need the C runtime (and any supplemental libraries the binary was linked against) and, optionally, /bin/ed – for interactive use, a controlling terminal is highly recommended because job control does not work without one.

To make full use of mksh(1)’s interactive features, it is recommended to copy the dot.mkshrc file from the source distribution as ~/.mkshrc into the user’s home directory and let the user adjust it to suit his needs. The sample file configures a few aliases and shell functions as well as a sensible prompt ($PS1) and some csh-like directory stack functions and zsh-like hooks. Full use of this file requires a few special UNIX® tools, e.g. readlink(1) with the -f flag.

Support

We provide an online manual page in HTML and PDF format. Reading books about Korn Shells in general is recommended as further help, but beware of the differences to other shells. Some ISBNs are listed at the end of the manual page.

If you require additional assistance or want to discuss bugs, features or enhancements, write to the mailing list (or subscribe to it). The mailing list can be reached via NNTP or at the MARC web archive (or GMane Loom) as well. Joining the IRC channel at Freenode (irc.freenode.net:6667) #!/bin/mksh (no joke, this is really the channel’s name) and #ksh (where you must distinguish AT&T ksh from mksh though) is recommended as well.

Installation

Skip to the section about being included in operating environments unless you really want to compile mksh from source yourself or create a package for your operating system of choice.

First off, you have to download the source code from any of the mirrors listed below, or any other mirror you know of. Official source code distributions are a cpio(1) compressed “old-style” (portable octal) archive, compressed with gzip(1) (zlib’s deflate algorithm) and digitally signed with gzsig(1) using the MirOS Project’s current signature key. Please verify the signature as well as the hashes and/or checksums below, so you’re sure the content is intact and the version number on the archive is correct. If you require source code in tar(1)’s “ustar” format, check the Debian Project for availability, although they often do not carry the latest version. The pax(1) utility (the POSIX Archiver) can extract from the CPIO distfile and is available even on a stock Microsoft® Windows® installation.

Known Mirrors

Checksums and Hashes

Decompression

Use any of the following syntaxes to extract the distfile; you’ll get the idea soon. Some web browsers (prominently, Mozilla® and its derivates as well as Microsoft® Internet Explorer®) already inflate the distfile during download but do not remove the “.gz” extension; replace “gzip -dc” (gzcat) with “cat” if that happens for you.

The first example is using BSD paxtar (MirOS BSD, OpenBSD, NetBSD®), or “bsdtar” (DragonFly); the second and third use cpio(1) or pax(1) and are for most operating systems; the fourth is for Debian.

Compilation

Now you’re in the source code directory; Build.sh does all the magic for you. In theory, invoking the command
% /bin/sh ./Build.sh
should work. Relative paths can be used too, for example, instead of cd(1)ing to the source directory, you could’ve done
% mkdir build; cd build; /bin/sh ../mksh/Build.sh

The build script requires a bourne shell (Solaris /bin/sh or the Heirloom sh, korn shell (ksh, ksh88, ksh93, pdksh, mksh, oksh, maybe the MKS ksh), POSIX shell (posh, /usr/xpg4/bin/sh, ash, dash), or a super-set (GNU bash) to work; the Z Shell could work too, but the C shell (csh, tcsh) or “bsh” or a scripting shell like the wish won’t. Accepted arguments are:

The build script also honours the following environment variables:

If CPPFLAGS contain any of the following definitions, the resulting binary will be compiled with a specific flavour:

You can override certain mirtoconf checks by setting environment variables like HAVE_REVOKE=0 (default for Linux) – if these are set to 0 or 1, the values are used; if unset, the values are probed (unless overridden by a different check, such as MKSH_SMALL), if set to ‘x’ the probe is forced.
Useful items to enable/disable are HAVE_MKNOD and HAVE_READLINE (set to 0 to disable, set to x to re-enable for MKSH_SMALL), HAVE_SETLOCALE_CTYPE (set to 0 if you know that it won’t ever return UTF-8), HAVE_PERSISTENT_HISTORY (0 to not include this feature).

Operating Environment specific notes

Compiler: ACK

Support for ACK on Minix 3 will be added after mksh works on Minix 3 with GCC. Support for other ACK versions or targets can be user-contributed.

Compiler: Borland C++ Builder

This compiler is somewhat supported in mksh R30 with UWIN’s cc wrapper. (We haven’t been able to produce a working executable though.)

Compiler: DEC/Compaq/HP C for OSF/1 and Tru64

This compiler is fully supported with mksh R33b (partial support did appear earlier).

Compiler: Digital Mars

This compiler is somewhat supported in mksh R30 with UWIN’s cc wrapper and a few kludges. (We haven’t been able to produce a tested executable though, due to general stability issues with the UWIN platform.)

Compiler: GCC

The GNU C Compiler 1.42, 2.7.2.1, 2.7.2.3, egcs (gcc 2.95) and the GNU Compiler Collection (gcc 3.x, 4.x) are known to work, but not all versions work on all targets. Specific C flags, known extensions, etc. are autoprobed; cross-compilation works fine. Use of gcc 4.x is discouraged because of several dangerous changes in how the optimiser works; it is possible to work around their trading off reliability for benchmark-only speed increases, but because mksh developers do not use gcc 4.x this will have to be user-contributed. On the other hand, gcc 3.x (in some cases 2.x) is the best choice for compiling mksh.

On BSDi BSD/OS, where gcc 1.42 and gcc 2.7.2.1 are available, the cc(1) manual page mentions that gcc 1.42 produces more reliable code, so we recommend to build mksh with CC=cc (gcc1) instead of CC=gcc or CC=gcc2 there instead.

Since mksh uses ProPolice, the Stack-Smashing Protector, some GCC versions’ compilates require additional shared libaraies.

Compiler: HP C/aC++

HP’s C compiler (/usr/bin/cc on HP-UX) is supported in mksh R30 and above; on IA64, only the LP64 model can be used; mksh segfaults in the ILP32 module (or rather, the system libraries do, I think), so it is default. PA-RISC too works fine, so this compiler is a primary choice.

Compiler: IBM XL C/C++ / VisualAge

IBM xlC 9.0 on AIX is supported in mksh R30 and above.

IBM xlC 8.0 on Linux/POWER and IBM xlC 6.0β on MacOS X are on the TODO.

Compiler: Intel C/C++/Fortran

ICC emulates GCC quite well (too well for my taste), is fully supported in mksh R30 and above on several platforms, but spits out lots (and I mean huge ugly lots) of bogus warnings during compile. We’re not going to work around these; let Intel fix their compiler instead. Some of these warnings were even responsible for bugs in mksh.

I could not get the Intel Compiler 10 for Windows® to work.

mksh enables the ICC stack protector option automaticaly. Compilates usually require the Intel shared libraries to be around.

Compiler: LLVM

Apple llvm-gcc from Xcode 3.1 had full success with mksh R34.

Vanilla llvm-gcc works fine as well.

Vanilla llvm-clang produces output which fails 83% of the test suite.

Compiler: Microsoft® C/C++

Support for the Microsoft® C Compiler on Interix and UWIN, with the respective /usr/bin/cc wrappers, appeared in mksh R30. The following product versions have been tested:

CL.EXE: Microsoft (R) 32-bit C/C++ Standard Compiler Version 13.00.9466 for 80x86
LINK.EXE: Microsoft (R) Incremental Linker Version 7.00.9466
(both are part of the .NET Common Language Runtime redistributable)

CL.EXE: Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.42 for 80x86
LINK.EXE: Microsoft (R) Incremental Linker Version 8.00.50727.42
(both are part of Visual Studio 2005 C++ Expreß)
You’ll have to change Interix’ cc(1) wrapper though: replace /Op with /Gs- to disable the stack checks (missing support in libc for them, they used to be off by default) and remove /Ze.

On Interix (SFU 3.5), this compiler is maturely usable and a good choice.

On GNU/Cygwin, using wgcc it might be possible to use this compiler. I could not test that yet, though.

On UWIN, this is usable as well.

Compiler: MIPSpro

Support for SGI’s MIPSpro compiler on IRIX appeared in mksh R33b.

Compiler: PCC (BSD)

Support for the Caldera/SCO UNIX® based, BSD-licenced portable C compiler in the ragge version has been added with mksh R31d. Versions from end of April 2008 onwards are known to work reliably, even with -O enabled.

The compiler itself rarely works on GNU/Linux or Darwin due to GNUisms, assembler problems, etc. though.

Compiler: SUNpro

Support for the SUN Studio 12 compiler (cc 5.9) as well as cc 5.8 appeared in mksh R30; other versions might be supported as well. This compiler is a primary choice.

Compiler: tcc (Tiny C)

Support for Fabrice Bellard’s tcc appeared in mksh R31, although its unability to do ‘-E’ in older versions gave us some headache, and glibc currently makes it impossible to link the final executable.

Compiler: TenDRA (maybe Ten15 too)

Support for TenDRA appeared in mksh R31 and appears to be solid; mksh uses the ‘system’ profile for compiling by default. Users who wish to build mksh with a different profile are welcome to help to port it.

See ULTRIX for an example of getting a ‘POSIX’ profile to work.

Compiler: DEC ucode (MIPS CC)

Since mksh R33c, ucode on Ultrix is fully supported. OSF/1 2.0’s ucode version cannot be supported as of now, as we don’t know how to determine linkage failures: the compiler returns errorlevel zero, an a.out file is generated and has executable permissions.

Toolchain: dietlibc

Fefe’s dietlibc works in mksh R34, although his opinion towards certain standards, such as caddr_t, strcasecmp(3), etc. are weird.

OS: AIX

Support for AIX with xlC appeared in mksh R30.

If passing custom LDFLAGS, don’t forget the export symbols required for using libcrypt. If passing custom LIBS, don’t forget -lcrypt.

OS: BSDi BSD/OS

BSD/OS 3.1 works fine with mksh R33.

OS: GNU/Cygwin

This operating environment is supported as much as it adheres to standard POSIX/SUSv3 conformant things. No workarounds for .exe suffixes or other platform-specific quirks have been or will be added.

OS: Darwin / Mac OSX

Works pretty well.

OS: DragonFly BSD

Perfect choice.

OS: FreeBSD

Perfect choice.

OS: GNU/HURD

This operating system is supported (on i386) since R29 but not well tested. mksh is part of Debian GNU/HURD, so it is expected to work.

OS: GNU/k*BSD

This operating environment has been supported for quite a while as part of Debian and somewhat tested.

OS: GNU/Linux

While POSIX does not apply to “GNU’s Not Unix”, the FHS (ex-FSSTND) does; please convince your distributor to move ed to /bin/ed if not already done. Manual page installation paths are not standardised in older distributions either.

Besides glibc (GNU libc), dietlibc (from Fefe), µClibc (embedded), and libc5 (on Linux 2.0.38) work, but locale detection is not automatic.

mksh can be used as /bin/sh on Debian and similarly strict distributions, which allow to use e.g. ash/dash there as well.

OS: HP-UX

Support for HP-UX with GCC appeared in mksh R29 and works with HP’s C compiler and is no longer experimental in mksh R30. Please use stty(1) to make the terminal sanely usable.

If passing custom CFLAGS, don’t forget -mlp64 (GCC) or +DD64 on Itanium.

OS: Interix

We have only tested SFU 3.5 on Windows® 2000, not SUA on Windows® 2003 SR1 or the version integrated into Vista.

As the Unix Perl which comes with Interix is too old, and the ActiveState Perl has… other issues, to run the regression tests, please install Perl from NetBSD® pkgsrc® instead.

As of mksh R30, the native compiler (cc(1)) is supported in addition to gcc, calling Microsoft C. Do not use the c89(1) wrapper.

If passing custom LIBS, don’t forget to add -lcrypt or any other library providing arc4random(3).

mksh can replace /bin/ksh and /bin/sh without any problems.

OS: IRIX

Support for IRIX64 6.5 appeared in mksh R33b.

OS: MidnightBSD

mksh is part of MidnightBSD 0.3 and above and used as native /bin/ksh; it almost certainly can be used as /bin/sh as well.

OS: Minix

Minix 3 is not supported yet – we were able to create an executable, but it did not run properly due to job control issues, similar to Plan 9. Minix 1 and Minix 2 will never be supported due to size constraints on 16-bit platforms, unless a user contributes code.

OS: MirBSD

Perfect choice. This is where mksh comes from.

OS: NetBSD

Perfect choice.

Starting with NetBSD 1.6, mksh can replace /bin/ksh and /bin/sh without any problems. On NetBSD 1.5, mksh can only replace /bin/ksh safely.

OS: OpenBSD

The setlocale(3) call in OpenBSD’s libc will always return the “C” locale and therefore has been disabled by default.

mksh can replace /bin/ksh and /bin/sh without any problems.

OS: DEC/Compaq OSF/1, Compaq/HP Tru64

Digital Unix is somewhat supported using gcc as of mksh R31b. With mksh R33b, many more versions and the native compiler work.

OS: Plan 9

Plan 9 is not supported yet – we were able to create an executable, but it did not return to the prompt after running a non-builtin command; this is job control issues, and patches are welcome.

Due to the unavailability of ttys, job control will never be supported.

The APE (ANSI’n’POSIX Environment) is required to build mksh; I don’t remember which compiler I used, but I think it was GCC.

OS: PW32 on Win2k

PW32 is not supported yet – killpg() and getrlimit() are missing, and it’s possible that PW32 and Minix 3, at least, need job control disabled or worked around. Maybe peek at how ash/bash for PW32 do it. gcc works.

OS: Solaris

Solaris is full supported since “forever” with gcc, and since mksh R30 with Sun’s C compiler. Both 32-bit and 64-bit modes work; 64-bit mode is not enabled by default by Build.sh, you must do that manually by passing CFLAGS of -O2 -m64 or -xO2 -xarch=generic64.

Solaris does not come with Berkeley mdoc macros for nroff, so using the HTML or PDF versions of the manual pages or pregenerating a catman page on another OS is required.

OS: Syllable Desktop

This does not yet work due to a signal passing bug in the AtheOS kernel, we were told by their developers. However, mksh R33 is at the same level of support as Plan 9 now.

Syllable Server will work, as it is, at the moment, “just” a GNU/Linux distribution with a different GUI. This may change though.

OS: ULTRIX

Even on ULTRIX 4.5, mksh R33c works fine. The system ksh must be used for running the Build.sh script, though.

You however must pass the -YPOSIX option to the ucode compiler, as the default -YBSD profile produces a broken executable (spins instead of starting up), and the -YSYSTEM_FIVE profile does not even compile. See TenDRA for another OE which has issues with different OE profiles.

OS: UWIN-NT

Compilation of mksh R30 on UWIN works with several compilers (bcc, dmc, msc – I could not get gcc-egcs, gcc-2.95, gcc-mingw, icc to work) but the platform itself is very flakey, and even some regression tests crash, due to target limitations apparently. Within these limits, mksh is usable.

After compiling

The Build.sh script generates an executable (“mksh”, except on GNU/Cygwin, where it is called “mksh.exe”), a shell script to use the newly built mksh to run the regression test suite (“test.sh”), and (unless the -r option was given) a pre-formatted manual page (“mksh.cat1”). It also lists installation instructions unless -q or -Q were provided. Now it’s the time to run
% ./test.sh -v
in order to see if the shell works.

To actually install mksh, copy the binary to some place in $PATH, i.e. /bin/mksh, $HOME/.bin/mksh, /usr/local/bin/mksh, or whatever your packaging system wants; strip it and run chmod 555 on it. (This can easily be achieved with install(1) – on Solaris, this is /usr/ucb/install not /usr/bin/install – with the arguments -c, -s, -m 755¹, and -o/-g. ① with 555, strip(1) cannot write the file any more, chmod 555 afterwards.) Also append its installation path to /etc/shells, install the dot.mkshrc file (usually alongside with the copyright file and other documentation), copy it to /etc/skel/.mkshrc if your operating environment has this means to include default dotfiles; install either the catman page (mksh.cat1) to, for example, /usr/share/man/cat1/mksh.0, or the mdoc page (mksh.1) to the standard location (/usr/share/man/man1/ or /usr/man/man1/ or whatever your operating environment requires). The manual page requires the Berkeley mdoc macros (either the BSD or the GNU groff version) to be installed during formatting time.

For packagers: Upgrades

At Freshmeat you can subscribe to get automatically notified (with a summary of changes, not the complete changelog, see below) whenever new releases are put out.

Note: This is not the ChangeLog, these are the packager-visible upgrade notes regarding changes in the build system (Build.sh and friends, compiler support, packaging conventions, bad examples, etc).

mksh R35b builds on some more platforms and throws less warnings, but the build system is almost unchanged; test.sh now shows the Perl binary used (honours $PERL) and its version.

In mksh R35, setlocale/nl_langinfo have been disabled by default for some platforms. If we do not assume UTF-8, disabling lets mksh employ the LANG and LC_* environment variables for codeset determination. Also, a new builtin is included depending on existence of the readlink(3) function, disabled by default if MKSH_SMALL. The “pdksh” check category is no longer persistent. The licence has changed (the advertising clause was removed). The dot.mkshrc sample was changed to improve re-use.
There was no R34.

No changes in mksh R33c except for Ultrix support. None in R33d.

In mksh R33b, much more compilers are detected, even if not all of them are supported. The OE (OS and CC/LD) versions are now dumped too. Instead of #error, forced link failures are now used as the mechanism to auto-detect some things in the target environment. Features are now much better detected, and some annoying warnings don’t show up any longer due to this. Less tools are required to build.

Please be reminded that you should run ./test.sh -v inside an environment with /dev/tty available (as device node) and usable (e.g. use script(1) or GNU screen if you’re doing auto-builds detached from controlling terminal). Use -v to see failures.

No surprises in mksh R33 either, but the build system now gives more detailed output on the version actually built, to aid tracking down FTBFSen (build errors) with access to only the build logs. Regression tests now work with Intel’s compiler on SLES too, which requires a custom LD_LIBRARY_PATH formerly stripped by the script.

No surprises in mksh R32, but some ancient systems (AIX, Solaris 11, OSF/1, UWIN) are now better supported.

In mksh R31d, parallel make with ‘-j’ was added (no limitation on number of childs though), this even works with Solaris 8 /bin/sh. The MKSH_NEED_MKNOD define is no longer honoured.

From mksh R31 to R31b, arc4random.c has been upgraded.

From mksh R30 to R31, there are no surprises. The “arc4random.c” file is available from mircvs://contrib/code/Snippets/arc4random.c now, and the new “source” command is not available in posix mode either.

From mksh R29 to R30, the following things should be kept in mind:

The syntax of Build.sh has changed: $CC now defaults to “cc” instead of “gcc”, and the ‘-d’ and ‘-nd’ arguments are gone – if you want to build a statically linked mksh, pass LDSTATIC=-static (gcc+GNU ld, adjust for other OEs) to it. An “arc4random.c” is now automatically included into the build if found in the source directory. The $CPP variable is ignored, $CC -E is used instead, except for tcc, which uses “cpp -D__TINYC__” because “tcc -E” doesn’t work.

As a tribute to better POSIX compatibility, certain aliases (like “stop”) are no longer predefined in “set -o posix” mode, which is invoked automatically if the shell is run as -sh, /bin/sh or similar, so that they can be used as function names.

If defining MKSH_SMALL, the ‘vi’ editing mode is omitted, which may surprise your users.

Many compilers other than gcc are now supported as well as AIX.

Inclusion in other operating systems

These packages are not official and have not always been tested by mksh developers; please keep this in mind.

Other Shells and more

mksh is a successor of pdksh but not affiliated with the pdksh developers or contributors. mksh is not affiliated with the AT&T Korn Shell, its past or present owners, other than that both attempt to implement the Korn Shell programming language.

mksh targets users who desire a compact, fast, reliable, secure shell not cut off modern extensions; a shell with Unicode support; an actively developed, current, and portable product; one with developers that listen to their users’ requests and implement them if they actually make sense.

mksh aims to replace pdksh in all but very rare use cases (such as support for checking the Unix mbox) and in all operating environments (thus including patches from pdksh on e.g. Debian).

Differences

mksh is a direct descendant from the OpenBSD /bin/ksh and contains all of its bug fixes and enhancements except the “GNU bash-like $PS1” and “ulimit can handle multiple limits in one invocation” changes. The DeliLinux developer who is responsible for packaging oksh for GNU/Linux should instead use mksh and port that diff over (be careful to not break the fixes to the command line editing modes, these are subtilely broken in OpenBSD). Even better, the OpenBSD people should not only commit a port of mksh but replace their ksh with it (optionally retaining that GNU bash-like $PS1 stuff). The set -o emacs-usemeta command is no longer needed because the emacs editing mode has been changed for Unicode/UTF-8 mode, which adds a new set -o utf8-hack mode. The set -o sh command has been completely removed, set -o posix merely turns off brace expansion as side effect. There is no limit (well, 2³¹ probably) on array sizes any more. Many bugs and security holes have been closed in mksh and are still in oksh and OpenBSD ksh. The user interface has much less bugs and surprises; emacs editing mode is enabled by default. In contrast to oksh, set -o arc4random can be used to control which generator for $RANDOM is used.

mksh is the heir of pdksh and contains all the latest fixes from upstream (so ca. 1995) and Debian, except a change which breaks (at least) BSD make due to different errorlevel (return/exit code) handling. See above for other differences. The code really has been cleaned up and no longer contains any material under licences more restrictive than the BSD licence.

AT&T ksh88 and ksh93 compare to mksh substantially, but share no code; the user interface is slightly different especially for ksh88; many editing commands work (only slightly) differently as well. mksh implements many, but by far not all, ksh93 features, but most ksh88 features. No floating point. The last command of a pipeline is executed in a subshell.

mksh can do many things GNU bash can’t, for example better arrays, the ksh Co-processes, etc. but is much faster and smaller. In contrast to bash, mksh is still being actively developed (bash almost only receives small changes or weird stuff like programmable tab completion). GNU bash’s array initialiser syntax is not yet supported. We don’t aim at being fully bash compatible, but some of the surprises for converts will be removed.

The Z shell (zsh) isn’t even remotely ksh compatible in its “emulate ksh” operation mode, and we don’t compare to it.

mksh is mostly bourne shell compatible (but ^ as alias for | is not supported, like most modern shells). mksh is also POSIX sh compatible. Some constructs are not supported, for example
((foo; bar) 2>&1 || baz)
which has to be rewritten as
( (foo; bar) 2>&1 || baz)
because ((…)) is shell arithmetics; brace expansion is turned on by default; etc.

mksh R33 supports even more bash/ksh93/zsh constructs than its predecessors; sometimes, not all cases (e.g. applying string trimming on arrays) are supported, but you probably will not notice that.

Official Testing

The MirOS Project has tested mksh on the following operating systems, asked people to test, and hunted mksh down in these packaging systems:

Current Release

Development Versions older than last release

Older Releases

Known to FAIL Build or Test

Recommendations on version numbering

mksh by default uses a version numbering scheme that uses full integers, prefixed by a capital letter R significing “Release”. If minor updates are required or requested, a lower-case letter from the standard latin alphabet will be appended, starting at ‘b’ and ending at ‘z’ (but usually way before or at ‘i’). If a packaging system cannot handle version numbers such as mksh-R29b (source) → mksh-R29b-1, mksh-R29bp1 (binary), packagers OUGHT TO map this to a numerical system as follows: mksh-29.2-1, mksh-29.2.1, mksh-29.2nb0, depending on the packaging-system local policy for build numbers / patchlevels.

Schemes to AVOID are mirbsdksh-1.29b, mksh-2.9.2, or worse. Please adhere to our recommendations so that users are able to locate mksh in their operation environment of choice.

/bin/ed

While we’re at it – recommendations for packagers – there is another set of do’s and dont’s: location of the UNIX® standard text editor. As outlined in traditional unixoid operating system standards, manifested into POSIX, and – for these three-letter words that aren’t Unix, no matter which of the kernels they use in their variety of so-called distributions – the FHS (FSSTND): ed lives in /bin/ed, period.

Patching mksh’s to look for ed in ANY other location is a MUST NOT.

Future Plans

Recent Changes

Changes in the current (unreleased) development version:

mksh R35b comes with the following bug fixes:

mksh R35 comes with helluva changes:

mksh R33d is a quick security-update with these changes:

mksh R33c issues fixes for the following issues:

mksh R33b comes with the following minor fixes:

A release with many new features is mksh R33, look yourself:

Sported by mksh R32 are these changes:

Everyone should upgrade to mksh R31d with fixes for…

The mksh R31c (Solaris-only) upgrade for cnuke@ was caused by:

A quick upgrade, mksh R31b with major bug fixes:

mksh R31 was released as part of MirOS #10 with these news:

A milestone in development: mksh R30 can do this:

older changes

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Generated on 2008-08-03 00:31:32 by $MirOS: www/mk/htsconv,v 1.26 2008/07/25 16:44:19 tg Exp $ from $MirOS: www/src/mksh.hts,v 1.162 2008/08/02 17:53:53 tg Exp $