Show HN: Kosh – Bash shell runtime with 100x faster Shellcheck and LSP built-in Kosh 0.1.0, a Bash-compatible shell runtime with built-in linting and a language server, claims to run ShellCheck diagnostics roughly 100x faster and execute scripts 5x faster than Bash. The project, renamed from 'shit' to 'kosh' in version 0.2.0, includes about 300 built-in diagnostics and supports Windows, Linux, and macOS. 0.1.0 has been released See the Release Blog Post https://fennec.support/scribbles/shell-release . 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 /toiletbril/kosh/blob/master/docs/kosh.1 for a fuller explanation: bash $ 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 https://github.com/fish-shell/fish-shell . 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 of zoxide https://github.com/ajeetdsouza/zoxide . bench provides built-in benchmark infrastructure inspired by Performance Optimizer Observation Platform poop https://github.com/andrewrk/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 , and rm . - Search utilities include find and grep . - Process utilities include killall , pkill , ps , timeout , and nproc . - Minimal implementations of calc and make 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 , and printf from the host. - The full test suite needs cat , cmp , diff , find , grep , head , sed , and strings . Interactive tests also need script and stty . Process supervision needs setsid 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 uses cosmoc++ 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. bash $ make MODE=