wolysh v0.5.0

wolysh v0.5.0: Bash compatibility

Wolysh 0.5.0 implements most of Bash's scripting language. Control flow,
[[ ]] and (( )), parameter expansion and arrays, redirections and process
substitution, strict mode and traps, and the Bash builtins scripts depend on
now behave as they do in Bash 5.3. The test suite runs each of these areas in
both shells and compares the results.

Highlights

#!/usr/bin/env wsh
set -euo pipefail
trap 'echo "failed at line $LINENO" >&2' ERR

declare -A sizes=()
while IFS= read -r -d '' file; do
    [[ $file =~ \.([a-z]+)$ ]] || continue
    (( sizes[${BASH_REMATCH[1]}] += $(stat -c %s "$file") ))
done < <(find src -type f -print0)

for ext in "${!sizes[@]}"; do
    case $ext in
        zig|py) printf '%-4s %8d bytes\n' "$ext" "${sizes[$ext]}" ;;
    esac
done

• Control flow: if/elif/fi, case with ;& and ;;&, until,
  select, POSIX function definitions, local, time, [[ ]] (patterns,
  =~ with BASH_REMATCH, integer and file tests), (( )) and
  for (( init; test; step )).
• Expansion: ${var:=}, ${var:?}, ${var#pat}, ${var/pat/rep},
  ${var:off:len}, case modification, ${!name}; indexed and associative
  arrays; declare/typeset attributes; Bash integer arithmetic in $(( )).
• Redirection and quoting: exec redirections, {fd}>file, <>, >|,
  <( ) and >( ), $'...', extended globbing.
• Strict mode: set -euo pipefail, PIPESTATUS, set -x with PS4, and
  traps for signals, EXIT, ERR, DEBUG and RETURN.
• Builtins: Bash read, mapfile, getopts, printf (with %(fmt)T),
  type, command -v, hash, help, ulimit, pushd/popd/dirs, and
  more.
• Interactive shell: UTF-8 editing with a kill ring, undo, bracketed paste
  and vi mode; history expansion; programmable completion; keyword
  highlighting; PS1 escapes and PROMPT_COMMAND.

Upgrading from 0.4

These changes can alter what existing wsh scripts do:

• A bare word in a command argument stays literal: status=x; git status
  runs git status. Inside language expressions (if count > 10 {,
  print name) bare names still refer to variables.
• name=value no longer exports the variable to child processes; use
  export or env NAME = value.
• wsh -c 'cmd' a b sets $0 to a and $1 to b, as bash -c does.
• read returns 1 at end of input.
• An expansion error such as ${x:?message} stops a non-interactive shell with
  status 1.
• Functions take precedence over builtins of the same name.
• Native expression arithmetic rejects non-numeric operands instead of treating
  them as 0.
• Scripts no longer print [1] pid for background jobs; interactive shells
  still do.

Known differences from Bash

• $name on an indexed array expands to every element, as it does for wsh
  lists; Bash gives element 0. Use ${name[0]} in scripts meant for both
  shells, including for $BASH_REMATCH.
• BASH_COMMAND is not set.
• < and > in [[ ]] compare bytes rather than the locale's collation
  order.

Install or upgrade

Download wolysh-v0.5.0-linux-x86_64.tar.gz and its .sha256 file:

sha256sum -c wolysh-v0.5.0-linux-x86_64.tar.gz.sha256
tar -xzf wolysh-v0.5.0-linux-x86_64.tar.gz
mkdir -p "$HOME/.local/bin"
install -m 0755 wolysh-v0.5.0-linux-x86_64/wsh "$HOME/.local/bin/wsh"
"$HOME/.local/bin/wsh" --version

Ensure $HOME/.local/bin is on PATH. Source builds require Zig 0.16.0:

zig build -Doptimize=ReleaseFast -Dtarget=x86_64-linux -Dcpu=baseline

Verification

CI and the release workflow build for baseline x86_64, check that the tag
matches wsh --version, and run the unit, interactive and compatibility suites
before packaging. Most compatibility suites run each case in wsh and in Bash and
require the same output and exit status.

• 337 unit tests
• 37 interactive checks
• 319 compatibility tests

Benchmarks were not re-measured for this release; the packaged results
describe v0.4.0.

Full changelog