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oam/knowledge base/bash.md
2022-10-10 01:27:17 +02:00

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# Bourne Again SHell
## TL;DR
```sh
# Run a command or function on exit, kill or error.
trap "rm -f $tempfile" EXIT SIGTERM ERR
trap function-name EXIT SIGTERM ERR
# Disable CTRL-C
trap "" SIGINT
# Re-enable CTRL-C
trap - SIGINT
# Bash 3 and `sh` have no built-in means to convert case of a string, but the
# `awk`, `sed` or `tr` tools can be used instead.
echo $(echo "$name" | tr '[:upper:]' '[:lower:]' )
echo $(tr '[:upper:]' '[:lower:]' <<< "$name")
# Bash 5 has a special parameter expansion for upper- and lowercasing strings.
echo ${name,,}
echo ${name^^}
```
## Further readings
- [Trap]
- [Upper- or lower-casing strings]
## Sources
- [The Bash trap command]
<!-- internal references -->
[trap]: trap.md
<!-- external references -->
[the bash trap command]: https://www.linuxjournal.com/content/bash-trap-command
[upper- or lower-casing strings]: https://scriptingosx.com/2019/12/upper-or-lower-casing-strings-in-bash-and-zsh/