The MirBSD Korn Shell

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The MirBSD Korn Shell

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mksh(1) R50

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).

mksh Logo This page is always accessible via a redirection at http://mirbsd.de/mksh, which is the canonical homepage URI. There also is (most of the time) mksh on Freshmeat and an mksh project page on ohlol, a statistics site. mksh is experimentally tracked at Launchpad. Download the Logo as SVG if you want. There’s also a full licence terms overview.

mksh must always be written either “mksh” (all-lowercase) or “MirBSD Korn Shell” – there is no other spelling. It’s usually pronounced by spelling out the four letters m, k, s and h individually, or by saying “MirBSD Korn Shell”.

Introduction

The current version of mksh is mksh R50 from 29 June 2014.

Thanks to “Der Verein trash.net” for sponsoring access to a Solaris 8 box. 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. (Both are now defunct.) Thanks to Jupp “cnuke” Söntgen for building on AIX in Dresden nowadays. Thanks to HP TestDrive/PvP/DSPP/CLOE, which helps in keeping mksh portable to several Unixes and compilers, and track down some architecture- or glibc-specific bugs. (These days, HP-UX/IA64 only, though.) 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 and an iPhone 3G. 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 and Patrick “aptituz” Schönfeld 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 and offering to help with HP-sUX testing (now that HP TestDrive went down) and initial porting to Haiku, which was continued at CLT 2010 with help from Stephan Aßmus. Thanks to André “naaina” Wösten for ssh on a QNX box. Thanks to Olivier Duchateau for testing on Slackware and Zenwalk GNU/Linux. Thanks to Winston W. for spotting musl, and thanks to maximilian attems and H. Peter Anvin for almost fixing klibc. Thanks to RT|Chatzilla, Chris “ir0nh34d” Sutcliffe, and others for Win32 platform assistance. (Did I miss anyone? Mail me if so. Some of these are past, anyway.)

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 here for the people interested. Right now, you only need to know that mksh is a DFSG-free and OSD-compliant (and OSI approved) 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, and (for BSD compatibility on other operating systems) the 3-clause UCB licence and the ISC licence; full terms are available. 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 and oksh 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. The MirBSD Korn Shell is OSI Certified Open Source Software™ and its manual is Open Knowledge.

To compile mksh, you will need a Bourne or POSIX shell (Solaris /bin/sh is enough, the Z shell works), a C compiler, 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 on Win2003/Vista); GNU/Cygwin; UWIN; GNU/Linux (libc5, glibc, dietlibc, µClibc, some klibc systems are tested), Debian GNU/kFreeBSD, GNU/Hurd or GNU/Linux; Sun Solaris (8, 9, 10, 11), OpenSolaris; AIX; IRIX; HP-UX 11i; OSF/1; ULTRIX; Minix 3; NeXTstep (but not OpenStep 4.2); QNX; BeOS (with limitations) or Haiku; SCO OpenServer 5 (with limitations) or 6 or SCO UnixWare; …
To run the regression test suite, you will need a not too antiquated Perl optimally with POSIX.pm or Errno.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. Note that $ENV must not be set for mksh(1) to parse the ~/.mkshrc file at startup.

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 (ATTENTION outdated content behind that link) to other shells. Some ISBNs are listed at the end of the manual page.

The RSS feed collects news and wlog entries regarding mksh.

If you require additional assistance or want to discuss bugs, features or enhancements, write to the mailing list (or subscribe to it by sending an eMail to the postmaster telling which address to subscribe to which list(s) – in your case, the miros-mksh list, but we have more mailing lists). The mailing list can be reached via the GMane archive using either NNTP or HTTP, or at The Mail Archive, although not at MARC. Joining the IRC channel at Freenode (irc.freenode.net, SSL port 6697, insecure port 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. Alternatively, use the development version from CVS. Official source code distributions are 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.

Known Mirrors

Checksums and Hashes

Decompression

We’re using gzip(1)-compressed POSIX ustar(1) distfiles nowadays, so a simple tar xzf mksh-R50.tgz will work. It will create all files in a subdirectory ./mksh/.

Patching

If you’re a packager/vendor and need to patch mksh and deviate from the default behaviour for that version which is indicated from $KSH_VERSION, patch your shell to append a space plus a vendor-defined string (examples PLD, Debian) so they can be distinguished. I think this is a reasonable request.

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

It is optionally possible to place files, such as printf.c, into either the current or the source directory. It will need a compile option (see below) to be activated. printf.c is undesirable because it uses stdio, floating point and bloats.

The build script requires a Bourne shell (Solaris /bin/sh, the Heirloom sh, DEC OSF/1 V2.0 /bin/sh), Korn shell (ksh, ksh88, ksh93, pdksh, mksh, oksh, maybe the MKS ksh), POSIX shell (posh, /usr/xpg4/bin/sh, ash, dash), related shell (yash, J�rg Schilling’s bsh or sh, the Z Shell), or a Bourne or POSIX superset (such as GNU bash) to work; the ULTRIX /bin/sh or the C shell (csh, tcsh) or “bsh” or a scripting shell like the wish won’t.
Accepted arguments are:

Note: “-c somemode”, “-j” and “-M” are mutually exclusive. The least preferred of the actually compiling flavours is -j, and the one we consider best is -c lto (since it achieves the best optimisations). It is sometimes possible to use -j together with -c llvm to parallelise LLVM Bytecode generation, though.

The build script also honours some environment variables detailed at its end.

Operating Environment specific notes

[Minix logo]Compiler: ACK

Support for ACK on Minix 3 has been added in mksh R37c with a workaround a known ACK bug (the “const” bug); it is now perfectly usable.

Support for other ACK versions or targets can be user-contributed. It currently lacks a sane frontend supporting things like “cc -E” (ack -E is ignored), at the least, and does not yet process system headers like <sys/types.h>.

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: C68 (C386, etc.)

The Walkers’ C89 compiler is not supported at the moment, but this is mostly due to difficulties in figuring it out. Any people who actually got it to compile anything, especially for both Linux and Minix, for both i386 and m68k, please contact us.

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

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

The ucode based compiler, linker and loader for Digital UNIX (OSF/1) V2.0 on MIPS is supported since mksh R36. It may, however, be forced to link statically to work around a bug in the toolchain.

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.)

[GCC logo]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. Early 2.x versions (like 2.1) may make trouble. 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 libraries. To disable this, pass HAVE_CAN_FSTACKPROTECTORALL=0 in the build environment.

GCC and Valgrind do not always play well together, hence the build option -valgrind adding -fno-builtin to avoid gcc producing code that can access memory past the end of the allocation.

[HP-UX logo]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 used to segfault in the ILP32 module (or rather, the system libraries did, I think), so it was default. PA-RISC too works fine, so this compiler is a primary choice.

In mksh R39b and up, you must set CFLAGS='+O2 +DD64' on IA64 to get the same behaviour as previous versions; the 32-bit mode is now the default. The HP-UX bundled compiler /usr/ccs/bin/cc works as well as HP aCC, except of course that it does not optimise. (GCC and C99 extensions aren’t actually used by mksh.)

Compiler: IBM XL C/C++ / VisualAge

IBM xlC 9.0 on AIX 5.3 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.

IBM xlC 7.0 on AIX 5.2 is supported in mksh R35c and above.

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: libFirm/cparse

libFirm with the cparse front-end is indistinguishable from GCC and known to build mksh R41 just fine.

[LLVM logo]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 starting at r58935 produces working code with mksh R36b and up.

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.

[nwcc logo]Compiler: nwcc

Support for nwcc appeared in mksh R36b; it is recommended to use nwcc 0.8.1 with mksh R39c or newer. The stack protector is currently disabled because it introduces errors.

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. Intermediate bugs that may have appeared are just as quickly fixed.

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.

Using SUNWcc on MirBSD/i386

Preparation steps. We assume that Sun Studio is extracted under the /opt/SUNWcc directory and Linux emulation has been set up. From now on, $S is /opt/SUNWcc/sunstudio12.1 (when using an older version, no “.1” at the end).

$ cat $S/../MirBSD/ld                   # must be executable (0555)
#!/bin/mksh
set -A args -- "$@"
integer i=0
while (( i < ${#args[*]} )); do
        [[ ${args[i]} = -dynamic-linker ]] && args[i+1]=/usr/libexec/ld.so
        [[ ${args[i]} = -Y ]] && args[i+1]=/usr/lib
        let ++i
done
exec /usr/bin/ld "${args[@]}"

In $S/prod/include “mkdir MirBSD_orig” and “mv cc MirBSD_orig/”. In $S/prod/lib “mkdir MirBSD_orig” and “mv *.o MirBSD_orig/” then “mv MirBSD_orig/values-xa.o .” (we need this one).

Furthermore, run “make obj && make depend && make && make sunstuff” in /usr/src/lib/csu/i386_elf then copy the three files obj/sun_crt{1,i,n}.o to $S/prod/lib/crt{1,i,n}.o (they are the MirBSD glue code / startup files).

For some versions, you may need to ensure /emul/linux/lib and /emul/linux/usr/lib do not contain any *.so or *.o files, except for libbfd, libopcodes, libstdc++ (but 12.1 uses the native linker).

In 12, -xO2 is broken; in 12.1 optimisation merely lets ir2hf run out of memory even with ulimit -d ulimit -dS 1572864, hence, -xipo cannot be used either. ☹

Using SUNWcc on MirBSD to build mksh

 $ S=/opt/SUNWcc/sunstudio12.1
 $ LD_LIBRARY_PATH=$S/prod/lib/sys:$S/prod/lib:$S/rtlibs CC=$S/prod/bin/cc \
   LDFLAGS="-Yl,$S/../MirBSD" mksh /usr/src/bin/mksh/Build.sh -r
[tcc logo]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. The bounds checker is currently disabled as it causes segfaults. Some intermediate versions of tcc break every once in a while.

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.

Compiler: USL C

This is the vendor compiler on SCO OpenServer and SCO UnixWare. It is recognised from R40f onwards.

Distribution: OpenADK

This development kit provide the same support cross-platform, with µClibc, musl and/or glibc, and thus should behave the same on all supported targets.

Distribution: OpenWrt

This distribution provides the same support cross-platform, with µClibc and/or glibc, and thus should behave the same on all supported targets.

Platform: Android

Supported with OpenADK (static) and NDK (although the build process is currently not feasible with an Android.mk file but possible if the CPPFLAGS and signames.inc are pregenerated; sys_signame[] has been pushed upstream and is in Android 1.6). Integration into both AOSP and the Google master, as /system/bin/sh, has been done and it can be enabled on a per-target basis at the moment; mksh is shipped with Android 3.0 and newer releases and the standard shell of non-emulator builds on Android 4.0 and newer.

Platform: iPhone

This is just Mac OSX, compile (natively, or cross via the SDK) and copy.

Platform: Maemo

This is like Debian, and packaging is available via the Garage and the Extras repository. Helpers (for GUI integration and actual on device testing) seeked.

Toolchain: dietlibc

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

Toolchain: klibc

klibc needs -DMKSH_NO_LIMITS and can then use stock klcc as compiler wrapper (CC=klcc).

Toolchain: musl

Appears to work just fine in R41b and up.

OS: 386BSD

This seems to work with mksh R41, although on 386BSD-0.0new (anything older than 386BSD-0.1) you need to patch the kernel against a close-on-exec bug and a bug when switching the terminal between cooked and raw mode as well add an execve with support for shebangs and long command liness.

OS: AIX

Support for AIX with xlC appeared in mksh R30.

OS: BeOS

BeOS can, with limitations, be used with R40f and up. Job control is not working, and mksh must be rebuilt (once built) by running Build.sh with the same options again but using the just-built mksh as interpreter due to a severe pipe-related bug in the system sh. RT says that “BeOS 5.1(Dano)/PhOS/Zeta” can be supported. He is also trying to figure out how to support BeOS 5.0 and how to distinguish it from 5.1…

OS: BSDi BSD/OS

BSD/OS 3.1 works fine with mksh R33.

OS: Coherent

This is a somewhat experimental port in mksh R41. (More information will follow.) Set TARGET_OS=Coherent manually.

[Cygwin logo]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: Dell UNIX 4.0 R2.2 (SVR4)

This exot has been tested with R40f: gcc is absolutely unusable on this platform but the vendor compiler works.
Set TARGET_OS=_svr4 manually.

OS: MS-DOS, DR DOS, FreeDOS

DJGPP’s bash.exe fails to run Build.sh, thus this is currently not supported. (We tried!)

[DragonFly logo]OS: DragonFly BSD

Perfect choice. Note /bin/sh compatibility needs a quirk.

[FreeBSD logo]OS: FreeBSD

Perfect choice. Note /bin/sh compatibility needs a quirk.

[Hurd logo]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.

Starting with mksh R39b, there is no arbitrary limit on pathnames any more, as the operating system requires. (However, there are still other inherent limits in mksh, such as that of an interactive input line.)

[Debian GNU/kFreeBSD logo]OS: GNU/k*BSD

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

[Linux logo]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), klibc (for initramfs) and libc5 (on Linux 2.0.38) work, but locale detection is not automatic for some of them.

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

[Haiku logo]OS: Haiku

Haiku can be used with mksh R39c and newer with a recent kernel from r35836 and newer, ca. mid-2010 due to a bugfix wrt. signal handling. gcc4hybrid might not work, gcc2hybrid might work well.

[HP-UX logo]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. Windows 7’s works, gcc only though.

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: LynxOS

Although the promised evaluation version never arrived, someone managed to test mksh R40f on LynxOS 3.

[MidnightBSD logo]OS: MidnightBSD

mksh is part of MidnightBSD 0.2-CURRENT and above and used as native /bin/ksh; it can be used as /bin/sh as well with a quirk.

MidnightBSD 0.3 uses mksh as /bin/sh indeed.

[Minix logo]OS: Minix 3

Minix 3 is supported starting mksh R37b (gcc), R37c (ACK/adk cc). Minix 1 and Minix 2 will never be supported due to size constraints on 16-bit platforms, unless a user contributes code. You will need:

# chmem =1048576 /usr/lib/em_cemcom.ansi
# chmem =262144 /usr/lib/i386/as

Append the following line to main.c on Minix 3.1.2a or older:

void _longjmp(jmp_buf env, int val) { longjmp(env, val); }
OS: Ninix 3

Ninix 3 (Minix 3 with NetBSD® code) has first been working starting with mksh R40e (clang). More porting and tests are needed. This is different from “regular” Minix 3. Do be sure to set your TARGET_OS environment variable correctly.

OS: Minix-386

mksh R42 works on Minix-386 down to version 1.7.0 but not 1.5 due to OS limitations; you might have to compile on version 2.0 as the ACK bundled with 1.7 segfaults.

OS: Minix-vmd

mksh R42 works fine on Minix-vmd 1.7 with ACK.

OS: MiNT / FreeMiNT

Support appeared in mksh R40. Depending on the distribution you use, you must use pdksh with CC=gcc to run Build.sh – cc and bash are both too broken. Afterwards, you must use the just-built mksh (after moving it out of the build directory) to re-run Build.sh with the same flags, due to bugs in pdksh on MiNT as well.

Most things work. FD_CLOEXEC is broken, so filedescriptor privacy has POSIX level only. /dev/tty is usually unusable; it might help to symlink /dev/console there but break other things.

(At OpenRheinRuhr 2011, tg@ had access to a FreeMiNT distribution which did not seem to exhibit any of the mentioned problems. YMMV.)

[MirBSD logo]OS: MirBSD

Perfect choice. This is where mksh comes from.

OS: MSYS

mksh compiles on MSYS (that is something different from using MinGW for the nascent native WinAPI port; it’s basically an old version of Cygwin wrapped) with few issues.

[NetBSD logo]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: NeXTstep

Except for OpenStep 4.2 which has a completely botched POSIX library (although rumours are there is a libposix.a in existence that can be copied onto it), it works with R40f onwards. (Binaries of NeXTstep 3.3 can be copied onto OpenStep 4.2 and used there.) You need gawk.

[OpenBSD logo]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. mksh is supposed to be a superset of oksh (except GNU bash-style PS1, weird POSuX character classes, and an incompatible ulimit builtin change).

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. In fact, gcc sometimes segfaults, so use the vendor compiler.

[Plan 9 mascot]OS: Plan 9

Plan 9 is not supported yet. Due to the unavailability of ttys, full job control will never be supported. Input line editing likewise cannot work in drawterm. Currently, a kernel or APE bug requires the use of -DMKSH_NOPROSPECTOFWORK but this doesn’t produce a fully working mksh (some features cause the shell to hang).

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. Jens Staal reports success with kencc though, so I’d suggest using that instead.

OS: PW32 on Win2k

PW32 is not supported yet – killpg(3) is missing, and it’s possible that PW32 needs job control disabled or worked around, since a workable binary can be made with -DMKSH_NOPROSPECTOFWORK (note that this option produces a shell not supporting standard Korn Shell scripts). Maybe peek at how ash/bash for PW32 do it. gcc works.

OS: QNX/Neutrino

QNX/Neutrino (Perl: “nto”) support appeared in mksh R36b.

The QNX ed(1) used to fail the regression tests due to being broken; compile the MirBSD ed and place it in /bin/ to fix this, or get an updated ed from vendor.

OS: SCO OpenServer, SCO UnixWare

SCO OpenServer 5 lacks job support, which SCO OpenServer 6 and SCO UnixWare 7.1.1 appear to have working.

OS: SkyOS

RT managed to build mksh on SkyOS. It somewhat works, and the testsuite failures are probably all bugs in their POSIX layer.

[OpenSolaris logo]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: SunOS

On mksh R42, add -DMKSH_TYPEDEF_SIG_ATOMIC_T=int and -DMKSH_TYPEDEF_SSIZE_T=int in addition to -DMKSH_UNEMPLOYED -DUSE_REALLOC_MALLOC=0 and SunOS 4.1.1 with GCC 2.7.2.3 will work.

[Syllable logo]OS: Syllable Desktop

Needs retesting with mksh R40+ (port unfinished)

This OE is suffering from bugs, although R41 works better than ever before. When deactivating any and all job handling with -DMKSH_NOPROSPECTOFWORK it works a bit better. (Note that this option produces a shell not supporting standard Korn Shell scripts.)

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.

I could not get networking on ULTRIX 4.0 (SIMH) to work, so I could not test it there.

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. (Build.sh takes care of this automatically.)

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.

OS: Windows

Michael Langguth, partially under work sponsored by his employer Scalaris AG, is currently working on porting mksh to native Win32 (WinAPI) to complete the GNU utilities for Win32 with a native shell to have a free interoperability solution for scripting. Progress is promising, but still a long way to go. The result will probably not be part of mksh itself, but a separate product; some core patches will however end up in core mksh.

A beta version of this is available as announced in this wlog entry.

OS: Xenix

SCO Xenix 386 2.3.4a lacks too much functionality to be an mksh target. (RT tried!)

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 was provided. Now it’s the time to run
% ./test.sh -v -f
in order to see if the shell works. The regression testsuite will exit with errorlevel 1 if any tests failed that are not marked as allowed to fail (e.g. OS dependent) or expected to fail, 0 otherwise. Omit the ‘-f’ option if you do not have a fast (say 1½ GHz Pentium-M) machine.

The regression tests need a controlling tty. Please ensure you have one, even for bulk/dæmonised builds; you can use GNU screen or script(1) to provide one by running the testsuite inside it (see the Debian and OpenSuSE Buildservive packaging for examples of how to do it). If, however, you absolutely cannot get the necessary utilities and devices installed in the build chroot, run: ./test.sh -v -C regress:no-ctty

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.

Note that a ~/.mkshrc file will not be executed if $ENV is set and not empty, nor is there an /etc/mkshrc.

For packagers: Upgrades

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). This is also not the users' upgrade caveat list.
Packagers also please note: it’s mksh or “The MirBSD Korn Shell” (“MidnightBSD Korn Shell” is also appropriate), but never Mksh or somesuch!

R50: test.sh now uses $TMPDIR.

R49: There is now generated content at build time; it is known that this is beyond the capabilities of some shells such as Coherent /bin/sh. We plan to address this in a later release by rewriting the relevant parts in C, so that a host C compiler will, in addition to a target C compiler, also be required to build mksh.

R48b: Nothing of notewortiness.

R48: We now ship a Windows® icon; just ignore it if you don’t want it. We regularily update dot.mkshrc so you’d better think of a way for your users to get those updates.

R47: Overriding size(1) with $SIZE now works. Do take note of this GCC bug when trying to build mksh sticks / waits forever.

R46: New -DMKSH_BINSHPOSIX to complement the older -DMKSH_BINSHREDUCED. Some lksh stuff is now integrated.

R45: Neither -DMKSH_GCC55009 nor HAVE_SILENT_IDIVWRAPV nor -Wno-overflow are used any more; mksh employs unsigned integer arithmetic now and emulates signed integer arithmetics with defined wraparound using unsigned C integers. Oh, and a workaround for a workaround for a bug in GNU tar in dietlibc was added (hah, nested sentences are nice!).

R44: Please consider switching from R41-stable, which is now oldstable; this release is conservative wrt. R43 and may become stable.

R43: Unbreaks detection of sys_siglist[] and friends’ definitions. The Makefrag.inc generation shows the check categories.

R42b: Dear packagers, please consider subscribing to our miros-mksh mailing list or use the RSS feed. The testsuite is now run verbosely by default; use ‘-Q’ to quieten it.

R42: MKSH_DISABLE_EXPERIMENTAL was made a no-op again for this release, like MKSH_DISABLE_DEPRECATED was for R41. There is a new option DEBUG_LEAKS which is implied by DEBUG, which, in turn, you should never enable in production. Handling of time.h vs. sys/time.h and sys_errlist[] changed. The default dot.mkshrc now uses ${ foo;} constructs ipv $(foo) to save a fork(2) at the cost of using a file in $TMPDIR; adjust if you really need.

R41c: Dear packagers, please consider subscribing to our miros-mksh mailing list or use the RSS feed.

R41b: Some bugfixes in Build.sh and the code; GCC now adds -fno-asynchronous-unwind-tables.

R41: We’re using POSIX ustar archives now. Honours LDSTATIC (which is appended to LDFLAGS and, if not empty (e.g. consists of whitespace), adds more mksh-local code to to the build to avoid pulling in more libc code and improving LTO effect. The -long-options for Build.sh are gone. MKSH_SMALL no longer implies -fno-inline. A “legacy ksh” can now be built. A GCC bug may lead to assertion failures at Build.sh check time; in that case, you may use a workaround only if you ensure that a run-time test succeeds (i.e. must not cross-compile except if the result is manually checked afterwards): arith-mandatory in check.t must pass if -DMKSH_GCC55009 is given (the Debian and OpenSuSE Buildservice packages do the same test without using the Perl testsuite).

Warning! The current Build.sh interface will change in the future. With run-time checks, mandatory testsuite parts, etc. it’s already at its limit, and we’ll be needing a host compiler some time later, which will see it revamped. Do read the upgrade notes!

R40f: Honours AWK. Is a lot more anal wrt. using cached Makefile includes. Persistent history support may show up.

R40e: No longer tries to use GCC and C99 extensions. It has a run-time check in Build.sh which may trigger a core dump; when cross-compiling, preseed with HAVE_SILENT_IDIVWRAPV=0 in the environment to skip the check and always compile in the safety code; the check is for removing the safety code if it is not needed on the target machine (which obviously cannot be checked when cross-compiling) and segfaults if it is needed (by design). Support for various OSes has improved.

mksh R40d has several new options: test.sh ‘-f’ to enable running tests that need a fast machine; the preprocessor flag MKSH_DISABLE_DEPRECATED to disable code that is deprecated and scheduled for removal in the next version; updated dot.mkshrc.

mksh R40c got better support for OPENSTEP, Interix, kFreeBSD, MSYS, Hurd. No packaging changes worth mentioning, though.

mksh R40b changed dot.mkshrc and has a new option for disabling special handling the cat(1) builtin. The system and suid profile have moved to /system/etc/ for Android. Build failures (e.g. broken system includes abusing inline vs. broken GCC --combine) may now be caught earlier, so Rebuild.sh may not be available yet.

mksh R40 has substantially changed Build.sh options, CPPFLAGS, etc. and the testsuite now exits with an error code if tests fail. Please do review your packaging; contact us if necessary. Specifically for embedded systems (do not do this on desktops etc.), the ~/.mkshrc location can be changed at compile time. Several more operating systems are supported. setmode.c is gone and HAVE_MKNOD defaults to 0 now but can be explicitly enabled, provided your OS has setmode(3) and getmode(3), or it is provided in $LIBS. arc4random.c is no longer used, unless specifically called for by -DMKSH_A4PB (e.g. on Cygwin). Upgrade printf.c to the latest version if you use it. First release to officially support Android; quell aliasing “stop” and “suspend” there. MKSH_SMALL doesn’t imply HAVE_REVOKE=0 any longer.

older entries

Download the development version via CVS

You can use cvs(GNU) to download the development version of mksh(1), commonly called HEAD (or “trunk” to some). Beware of bugs though we strive to make it installable (at least on MirBSD ☺) at all times.

% env CVS_RSH=ssh cvs -qd _anoncvs@anoncvs.mirbsd.org:/cvs co -PA mksh

You might also want to get the printf.c builtin, but this is optional, strongly discouraged and use it only if you really must:

% env CVS_RSH=ssh cvs -qd _anoncvs@anoncvs.mirbsd.org:/cvs co src/usr.bin/printf

Installation instructions as above, although the Build.sh options, CPPFLAGS, etc. might have changed a little in the meantime. In general, you want the following:

% cd mksh
% sh Build.sh -r -c lto

Optionally set CC and other variables, as usual.

Inclusion in other operating systems

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

Users' Upgrade Caveat

This does not necessarily list new features, only these which users should be aware of for existing scripts.

R50: Arithmetic expressions are now IFS-split, as per POSIX; this matches what the manpage always documented. Due to regressions, the arr=([index]=value) syntax (naming the indicēs during setting an array) is gone for now, and will not reappear in “set -A”, only in the “=(…)” syntax once we get its parsing fixed. Privileges are now dropped upon start unless the shell is started with “-p”.

R49: The hash algorithm has changed (for, hopefully, the last time); the old algorithms are gone from dot.mkshrc too, and the ${foo@#} syntax no longer accepts a seed value (for more variety use the functions from dot.mkshrc; for hash tables, just xor and rotate the finished stable hash). Some terminal and other issues have been fixed, don’t be surprised.

R48b: Bugfix for multi-line prompts.

R48: The “doch” alias in dot.mkshrc now keeps standard input usable at the cost of the command to be run being logged by sudo(8). If you notice anything unusual (regression) in the interactive display code please report it; sections of that code have been refactored and improved.

R47: The -T option no longer chown(2)s or chmod(2)s the tty(4) device; it no longer fork(2)s if the argument is prefixed with a ‘!’ (MirBSD setsid(2) is a bit too anal to make use of it, but it gets rid of cttyhack et al. on Linux). POSIX compatibility was improved again (also thanks to the OpenBSD guys). New “set ±o inherit-xtrace”. Fixes lotsa bugs in R45/R46…

R46: Compatibility behaviour (mksh with -o posix, mksh with -o sh, mksh with -o posix -o sh, lksh, lksh with -o posix) changed again slightly. For both, -o posix re-enables parsing leading digit-zero numbers as octal, even though you should know better. You can now set both sh and posix but have to do it with the same command; your distributor can pre-enable both, or just one, for /bin/sh. The manpages for mksh and lksh document the delta better now and point out why you should not rely on POSIX long arithmetic.

R45: mksh in compatibility modes (posix, sh, lksh) no longer parses the &> GNU bash I/O redirection (it breaks previously valid scripts). “set -x” output changed. Enjoy the new dot.mkshrc provided PS4 variable and “doch” alias.

R44: "$@" always generates words.

R43: $'…' is only allowed where strings are.

R42b: Sorry for the “set -e” breakage.

R42: ${ foo;} constructs now handle local, return and exit like functions do; dot.mksh makes use of them to avoid fork(2)s. $'…' works in more places; here strings now use the full recursive parser.

R41c: Sorry for the “set -e” breakage.

R41b: The ERR and EXIT traps are called correctly; in “set -e” mode, functions correctly cause the shell to exit if they return nonzero, even if they contain a list.

R41: Deprecated features (set ±o arc4random; beginning an input line with ‘!’ instead of ‘r’+space) are gone. Numbers beginning with 0 are no longer interpreted as octal (except in lksh). Several fixes may have user-visible impact on the language.

For mksh R41 and up, being a feature superset of OpenBSD ksh (except the broken (GNU bash-style) PS1 and mail support) is demoted, no longer a primary but a secondary release criterium. This was changed to facilitate faster releases, especially when OpenBSD changes are not usable as-is.

R40f: Support for persistent history (which is still discouraged) may show up on platforms previously without it.

R40e: Interpreting "010" as octal number will now emit a warning at run-time. Several bugfixes lead to slightly changed behaviour to conform better to the standards. The worst offending bugs in the persistent history code have been fixed, but its use is still discouraged. THIS VERSION IS BROKEN WITHOUT A HOTFIX which your packager probably added. Tab completion may now shrink the current input line, but still follows the docs.

R40d: Interpreting "010" as octal number is now deprecated and will be removed soon. You can now use “local” and “set -A” together to create function-local arrays. The test(1) built-in command behaves POSIX conformant. The ^O Emacs mode command now works as it used to when editing the fetched lines. Arithmetic expressions have certain guarantees that are detailed more explicitly in the manpage.

R40c: The hack for when an interactive command begins with ‘!’ to substitute that with “fc -e -” is now deprecated and will be removed with R41 (or R42, we’ll see) despite objection. Write ‘r ’ (letter err plus a space) instead, it’s exactly the same. On the other hand, GNU bash-style array assignments are now a standard feature: x=(a [3]=b); x+=(c [6]=d) now works even in -DMKSH_SMALL. The -DMKSH_BINSHREDUCED fix for ${foo%\?} needed another fix, same for the recursive parser introduced in R40.

R40b: There is a new built-in special command “global” which does the same as “local” except localise every parameter it touches; in short, it does what “typeset” would’ve been supposed to be had it not to double as “local”. Tab completion will now work better. The shell handles bogus environment variable imports more gracefully and doesn’t let the terminal crash hard under some corner cases. ^Cing out of the built-in cat utility is possible.

R40: “set ±o arc4random” is deprecated and will not exist in the next version (R41) any more – the shell uses an LCG internally which is seeded from ASLR. Several POSIX fixes may change behaviour of builtins, substitutions, etc. and some differ now depending on the “set ±o sh” flag. New builtin “cat” (although, if called with a flag, the external cat utility is invoked) and “sleep” (if select(2) could be linked). dot.mkshrc no longer exports $PS1. GNU bash localised strings ($"…") are handled, but (of course❣) untranslated. “foo=<<EOF” cat(1)lessly assigns a here document to a parameter. New KSHEGID, KSHGID, KSHUID variables and PIPESTATUS array. Completely new read built-in command with several new options. Parse command substitutions – $(…) – recursively. HP-UX “test -H” is back, “test -t” (without the “fd” argument) is gone. “set -x” is now inherited by called functions. The x+=y and x+=(y z) notations for appending to variables and (!MKSH_SMALL) arrays are now supported, as are “;&” and “;|” (“;&&” !MKSH_SMALL too) case fall-through without/with re-examination.

older entries

Recent Changes

Changes in the current (unreleased) development version:

R50 is a recommended bugfix release:

R49 is a recommended bugfix release:

R48b is a minor bugfix update:

R48 is a small but important bugfix update:

R47 is a bugfix everyone must upgrade to:

R46 delivers these changes:

R45 comes with this bag of changes:

R44 contains these bugfixes:

Please upgrade to mksh R43 (or stick on R41c) because of…

mksh R42b and R41c fix regressions:

mksh R42 brings back the release\ {early,often} scheme:

mksh R41b is a bugfix-only release off a stable branch:

mksh R41 brings a number of bugfixes and new features:

mksh R40f fixes a critical bug as well as this:

mksh R40e is another must-have bugfix update:

mksh R40d is a must-have bugfix update:

mksh R40c collects stable development, mostly fixes:

mksh R40b introduces several desired fixes:

mksh R40 is a major everything release:

older changes

Future Plans

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