0.1.0 has been released! See the Release Blog Post.
The project was renamed in 0.2.0. The shit
is now kosh
, shitbox
is
koshkit
, and every prefix is changed to kosh
or KOSH_
. I got over the funny name. Thanks.
Koshka is the Russian word for a cat.
Koshka is an interpreter, interactive shell, formatter and a language server, with first tier support for Windows, Linux and macOS, fully compatible with Bash 5.3 and Dash.
Koshka contains ~300 built-in shellcheck diagnostics. It is usually 5x faster than bash, or ~100x+ faster than shellcheck, which makes it exceptionally friendly to coding agents or strict environments where Bash is still used.
| Koshka analyzing 20K-line shell script in ~0.05s |
|---|
kosh
is the koshka's binary.
Koshka aims to be a complete, faster and portable Shellcheck and Bash replacement. The shell guarantees first tier support for Linux, macOS and Windows, preserving equivalent behavior on either of these systems.
The shell is designed to work without absolutely no config whatsoever. Koshka's Linux binary is static and it does not use C++'s STL. Koshka also can work without coreutils, using it's own utilities.
The project is in early stage. There's no guarantee that it will not blow your computer up. Bug reports are greatly appreciated.
See the manual page for a fuller explanation:
$ man docs/kosh.1
Koshka runs in four modes, called moods, across three shell identities. ZSH
has similar idea behind it's emulate
builtin.
The default kosh
mood is a strict superset of Bash with analysis and
optimization enabled. The other moods are bash
, bash-posix
, and sh
. The
bash-posix
mood provides Bash behavior with its POSIX mode enabled.
Before it runs a command, Koshka analyzes and optimizes the complete script. The catalog includes about 100 checks derived from ShellCheck and about a dozen native analysis checks.
kosh --lint
behaves like shellcheck, but several magnitudes faster.
kosh --format
formats the code. There's no customization as of now.
kosh --language-server
launches language server on stdin.
The --mood
option, or -M
, selects kosh
, bash
, bash-posix
, or sh
.
The default is kosh
. A binary symlinked as sh
, dash
, or bash
selects
the matching mood and disables diagnostics. set --mood
changes the mood at
runtime. In the default mood, -W
retains the default severities, -WW
demotes lenient errors to warnings, and -WWW
also demotes strict errors. In
other moods, -W
enables strict warnings, -WW
also enables lenient warnings,
and -WWW
also enables annoying warnings.
The -I
option enables mimicry. Koshka detects sh
, dash
, and bash
shebangs and runs each script in the matching mood. The current diagnostics setting is preserved.
The --init-moods
option, or -L
, accepts a comma-separated list of moods whose startup files will be used. Its default value is the selected mood.
The KOSH_FLAGS
environment variable specifies default flags. A flag on the command line still wins.
When KOSH_FLAGS
or the command line contains an invalid flag or argument, a login shell skips its startup files and opens a rescue session.
The interactive mode is inspired by
fish. Shell provides syntax
highlighting, word movement, editing controls, UTF-8 support, display-width
handling for wide characters, multiline editing, history search, and persistent
history. kosh
does not depend on readline, so it's config is not used.
Koshka has more than 50 builtins, and each builtin supports --help
. These include Bash and POSIX builtins. The additional builtins include the following commands.
z
is a port ofzoxide.bench
provides built-in benchmark infrastructure inspired by Performance Optimizer Observation Platform (poop).assimilate
provides transactional installation on an SSH target.
The koshkit
builtin bundles a BusyBox-style set of small core utilities.
- File utilities include
cp
,mv
,ln
, andrm
. - Search utilities include
find
andgrep
. - Process utilities include
killall
,pkill
,ps
,timeout
, andnproc
. - Minimal implementations of
calc
andmake
are included.
koshkit cat --syntax-highlighting
colors shell files when standard output is a terminal. Shell extensions and known shell shebangs select the source. The output omits underline attributes.
This software began as a late April Fools' joke. It is written from scratch in a
macro-heavy C++23 dialect and is compiled with -nostdlib++
. The executable links only to the C library.
Development occurs on staging
, and the branch may be broken. The master
branch should pass all tests.
A native build needs the following tools.
- Install GNU Make, Clang 18 or later with C++23 support, libc development files, and headers for the target platform. Linux builds also need Linux kernel headers.
- The default debug build needs the AddressSanitizer and
UndefinedBehaviorSanitizer runtimes from
compiler-rt
. - The test suite needs Bash 5.3, Dash, and Python 3.
- The build and test scripts need
mkdir
,rm
,cp
, andprintf
from the host. - The full test suite needs
cat
,cmp
,diff
,find
,grep
,head
,sed
, andstrings
. Interactive tests also needscript
andstty
. Process supervision needssetsid
or Perl.
A complete Alpine setup can be installed with the following package set.
apk add --no-cache \
git git-doc make build-base musl-dev linux-headers clang llvm lld \
compiler-rt bash dash zsh yash busybox coreutils mandoc python3
The benchmark needs Bash, Dash, and Python 3. Zsh, Yash, and BusyBox ash provide
optional comparison rows. The coverage report needs llvm-profdata
and
llvm-cov
from the matching LLVM installation. Documentation checks use
mandoc
. Formatting and static checks use clang-format
and clang-tidy
from Clang 18 or later.
Each cross-compilation target needs its matching toolchain. Zig builds the Zig
targets and cross-compiles release binaries to Linux. MinGW-w64 targets Windows,
osxcross with a macOS SDK targets Darwin arm64, and cosmoc++
builds the Cosmopolitan modes.
The MODE
variable controls the build type.
rel
is an optimized build.prof
is an optimized build with debug symbols for profiling.cov
is an optimized build with debug symbols for collecting coverage.dbg
includes all symbols, AddressSanitizer, and UndefinedBehaviorSanitizer.cosmo
is an optimized build that usescosmoc++
from the Cosmopolitan toolchain.cosmo_dbg
is a debug Cosmopolitan build.
TARGET
defaults to the host platform and accepts Linux
, Windows_NT
, or
Darwin
.
A non-Windows host cross-compiles TARGET=Windows_NT
with MinGW. A non-Darwin
host cross-compiles TARGET=Darwin ARCH=arm64
with osxcross. Linux is a native target.
The $CXXFLAGS
environment variable appends flags to the build commands.
Build with GNU Make as shown below. Make uses every available logical CPU and shares its bounded job pool with recursive builds.
$ make MODE=<rel/prof/dbg/cov/cosmo/cosmo_dbg>
$ make MODE=rel TARGET=Windows_NT
$ make MODE=rel TARGET=Darwin ARCH=arm64
$ ./kosh --help
Zig can also build the dbg
and rel
modes.
$ zig build --release=fast
$ ./zig-out/bin/kosh --help
Install or uninstall the selected build with the following commands.
$ export PREFIX=/usr/local
$ make install
$ make uninstall
The running binary can install itself on an SSH target with assimilate user@host
.
Is it usable?
- Programs run.
- Linux and Windows are supported.
- Logical sequences are supported with
&&
,||
, and;
. - Pipes are supported.
- Redirections are supported with
>
and<
. - Shell expansions are supported with
?
,[...]
,*
, and~
. - Escapes are supported.
- Environment variables are supported.
- Numeric expressions are supported.
Is it good?
- Background jobs are supported.
- Scripting constructs include flow-control keywords.
- Blocks and functions are supported.
- The shell supports
sh
scripts.
Is it exceptional?
- The shell supports Bash scripts.
- ShellCheck-style warnings are built in.
- Koshkit replaces common Unix programs that are absent from Windows.
- Arbitrary-precision numeric expressions are planned.