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---
format: markdown
toc: no
title: Bash Shell
...
## Job Control
The syntax for "job number" or "JOBSPEC" (when using `kill` or similar) is
`%4` or `%5`.
## Startup
`bash` by default takes a very long time to initialize because the
auto-completion scripts are loaded multiple times; disable this in
`~/.bashrc`?
## Piping
You can pipe both `stdout` and `stderr` together either to a file or two another command::
grep --asdf >& /some/file
grep --asdf |& less
## Prelude
I frequently add a one-line version of the following to shell scripts:
set -e # fail on error
set -u # fail if variable not set in substitution
set -o pipefail # fail if part of a '|' command fails
Note that `join`, `grep`, and others sometimes exit non-zero return codes on
purpose (eg, pipe input closed or found no matches, as expected), which makes
life difficult. Sometimes `|| true` is enough to get around this.
## General Style
Google has a style guide: https://google.github.io/styleguide/shell.xml
Shellcheck is a lint tool: https://www.shellcheck.net/
http://redsymbol.net/articles/unofficial-bash-strict-mode/
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