j33ty/bash-cheatsheet.md

Last active June 3, 2019 20:24

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$\{var:-word}: If var is null or unset, word is substituted for var. The value of var does not change.

$\{var:=word}: If var is null or unset, var is set to the value of word.

$\{var:?message}: If var is null or unset, message is printed to standard error. This checks that variables are set correctly.

$\{var:+word}: If var is set, word is substituted for var. The value of var does not change.