- ${#v}, ${v#p} ${v##p} ${v%p} ${v%%p}, ${v/p/r} ${v//p/r} ${v/#p/r}
${v/%p/r}, ${v:off:len}, ${v-w} ${v:=w} ${v:+w} ${v:?msg}; nested ${}
- arithmetic expansion $((...)) with the C operators, ** and assignments
- set -e, set -x, set -o pipefail (also as gosh options, passed on to
subshells); set shows variables, set -o the options
- trap for EXIT and signals; scripts with an EXIT trap run it on
SIGINT/SIGTERM/SIGHUP too
- eval, exec (also exec > file without a command), $!, wait pid
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Go's syscall.WaitStatus decodes the "continued" status wrongly on BSD:
on FreeBSD it is read as killed by SIGCONT, so after bg the job was
reported as "Exit 147" and removed from the job table while it was
still running (fg: "no such job"); on macOS it is read as stopped.
The shell marks jobs as running itself when it continues them, so wait4
is called without WCONTINUED and only exited/signaled statuses finish a
process.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- in an interactive shell every pipeline runs in its own process group
and gets the terminal while it runs in the foreground
- Ctrl+Z stops the foreground job, command & starts a job in the
background; finished and stopped jobs are reported before the prompt
- new builtins jobs, fg, bg and wait (wait also works without job
control, e.g. in scripts, where background jobs read from /dev/null)
- terminal modes are saved and restored when a job stops or continues
- exit and Ctrl+D warn once if there are stopped jobs
- processes are waited for with wait4 (WUNTRACED) instead of exec.Cmd.Wait
- pty based test for job control (Linux)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Florian WaltherandClaude Opus 5.5