bashy — a pure-Go Bash 5.3 drop-in

bashy is a single static binary that runs Bash scripts and interactive sessions. It is written entirely in Go (no CGo, no system Bash required) and is a drop-in replacement for bash 5.3 — same command-line flags, same script semantics, same $BASH_VERSION — that passes GNU Bash's own 5.3 test suite (every runnable fixture; see Status below).

It is built on the qiangli/sh fork of mvdan.cc/sh, which carries the Bash 5.3 interpreter work. bashy is the user-facing shell; sh is the library.

Status: bashy passes 100% of GNU Bash's own 5.3 test suite — every measured fixture (86/86: 0 failing, 0 skipped) on Linux and macOS (see docs/TODO.md). That includes job control, coprocesses, signal traps, and locale-aware (non-UTF-8) globbing — features the early goroutine-based runner couldn't do, now implemented.

Known limitations: arithmetic uses the native int width, so 64-bit values on 32-bit builds (GOARCH=386) truncate (a 64-bit-int migration is tracked); and Windows builds and runs but its full test-suite run is still being verified. As in Bash itself (jobs.c vs nojobs.c), OS-level job control is a Unix feature.

Why

• No dependencies. One binary. No bash, no shared libraries, no package manager. Drop it on any host (including minimal containers and Windows) and run your scripts.
• Cross-platform. The same shell semantics on Linux and macOS (verified against Bash's test suite); Windows builds and runs, with full verification in progress.
• Embeddable lineage. The engine underneath (mvdan.cc/sh) is a mature, widely-used Go shell library, so behaviour is well-tested and hackable.

Install

Download a release binary

Grab the archive for your platform from the Releases page and put bashy on your PATH:

Platform	Asset
Linux x86-64	bashy-linux-amd64.tar.gz
Linux arm64	bashy-linux-arm64.tar.gz
macOS Intel	bashy-darwin-amd64.tar.gz
macOS Apple Silicon	bashy-darwin-arm64.tar.gz
Windows x86-64	bashy-windows-amd64.zip
Windows arm64	bashy-windows-arm64.zip

# Linux/macOS example
tar -xzf bashy-linux-amd64.tar.gz
sudo install bashy /usr/local/bin/bashy
bashy --version

With Go

go install github.com/qiangli/bashy@latest

From source

If bashy is already installed on the outpost, the source build can dogfood bashy's own tool surface: no host git, curl, wget, or make required. bashy git gets the sources, scripts/bootstrap-siblings.sh uses bashy git for sibling checkouts, and ./bashy dag build runs the build through bashy go (bashy's self-provisioning Go front end):

bashy git clone https://github.com/qiangli/bashy
cd bashy
./scripts/bootstrap-siblings.sh
./bashy dag build          # -> bin/bash and bin/bashy
./bashy dag install        # optional: install into GOBIN

On a host build of bashy with the container engine enabled, the same checkout can also be built inside a container with the host filesystem mounted through bashy podman; use that lane when the outpost should not depend on host build packages beyond the already-installed bashy.

The traditional host-tool path also works:

git clone https://github.com/qiangli/bashy
cd bashy
# bashy resolves the sh engine as a flat sibling. This clones it next door
# (../sh) at the SHA pinned in .sibling-pins:
./scripts/bootstrap-siblings.sh
make build          # -> bin/bashy

For a fresh checkout that wants to dogfood the DAG runner before this checkout's new bin/bashy exists, use the repo-local bootstrap launcher:

./bashy dag build
./bashy dag install   # installs bash/bashy into GOBIN; then `bashy dag ...` works
make dag ARGS=build   # equivalent bootstrap path if you prefer make

Usage

bashy script.sh arg1 arg2      # run a script
bashy -c 'echo "$BASH_VERSION"'# run a command string
bashy                          # interactive shell
echo 'echo hi' | bashy         # read a script from stdin

Supported flags

bashy accepts the common Bash invocation flags:

Flag	Meaning
-c <string>	run <string> as a command
-i	force interactive mode
-l, --login	act as a login shell
--posix	POSIX mode
--norc	do not read ~/.bashyrc
--noprofile	do not read profile files
--rcfile, --init-file <f>	use <f> as the interactive startup file
-o <opt>	enable a set option (e.g. errexit, xtrace)
-O <opt>	enable a shopt option
--pretty-print	pretty-print the parsed input
--version	print version and exit

Startup files: interactive shells read ~/.bashyrc (or --rcfile); login shells read /etc/profile and ~/.bashy_profile; $BASH_ENV is honoured for non-interactive shells.

Compatibility notes

bashy is a pure-Go runner: subshells are goroutines rather than fork(), and process substitutions use real named pipes. Job control (jobs/fg/bg/kill %n/suspend with stopped-state tracking), coprocesses, and signal traps are implemented and pass Bash's test suite on Unix. Mirroring Bash's own design (jobs.c on Unix, nojobs.c elsewhere), the OS-level job-control machinery is Unix-only; on other platforms it degrades exactly as a no-job-control Bash does.

Two known gaps: arithmetic currently uses the native int width (64-bit on 64-bit platforms), so very large values on 32-bit builds truncate — a tracked int64 migration; and the Windows test-suite run is still being verified. Everything else — parameter expansion, arrays and associative arrays, namerefs, [[ ]], arithmetic, here documents, brace/tilde/glob expansion (locale-aware, including non-UTF-8 charsets such as Big5/Shift-JIS), traps, printf, read, prompt escapes — matches Bash 5.3 and is verified against Bash's own test suite.

Development

See CLAUDE.md for the development workflow and docs/ for the compliance roadmap and per-fixture analyses. The compliance suite is driven by make test-bash (requires a local external/bash-5.3 symlink into a Bash source tree — see CLAUDE.md).

License

BSD 3-Clause (inherited from mvdan.cc/sh). See LICENSE.