task_010_parameter_expansion

Parameter Expansion

• Scripts
  • default vars shell
  • set -e with multiple scripts

www.gnu.org » Shell-Parameter-Expansion.html

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$ var=
$ : ${var:?var is unset or null}
zsh: var: var is unset or null
$ echo $?
1

$ var=""
$ : ${var:?var is unset or null}
zsh: var: var is unset or null
$ echo $?                       
1

$ var="a"
$ : ${var:?var is unset or null}
$ echo $?                       
0