Random Bash wisdom
I’ve recently found myself writing some bash scripts and I wanted to collect some random wisdom I aggregated:
1. This is a great cheat-sheet for bash if conditions: https://clburlison.com/bash-if-then-cheat-sheet/
2. If you have a back-up solution in case a certain command is not available in the PATH, you can use the following to test it:
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if ! command -v my_tool > /dev/null; then
# do something in case my_tool is not available
fi
NOTE: In bash, you can also use “hash” command, as this post summarizes: https://scripter.co/check-if-a-command-exists-from-shell-script/
3. To get the path of your own script:
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SCRIPT_DIR=$(realpath $(dirname "$0"))
4. Understanding Curly braces: https://www.linux.com/topic/desktop/all-about-curly-braces-bash/ Now, I don’t think every variable should be put in ${}, but it’s useful to have a reference on what you can do when using ${} instead of just the $ sign.
5. I like using pushd and popd, but I also like them to be silent. https://serverfault.com/questions/108154/can-i-call-pushd-popd-and-prevent-it-printing-the-stack shows how to do it:
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pushd mydir > /dev/null
# work in mydir
popd > /dev/null
Finally, the Wikibook on Bash Shell Scripting is realy good (https://en.wikibooks.org/wiki/Bash_Shell_Scripting).