I have a large number of variables in my script, and I want the script to error out if any one of the variables are empty.
I know I can:
if [[ -z "$var_1" ]] || [[ -z "$var_2" ]] || ... [[ -z "$var_n" ]]; then
# failure message
fi
However, I cannot inform the user which variable was empty if I do it in this way. Is there an alternative approach to the above so that I can inform the user about the empty variable?
#!/bin/sh
foo=(var_1 var_2 var_n)
for bar in ${foo[*]}
do
if [[ ! ${!bar} ]]
then
echo $bar is empty
fi
done
Just use ${var:?var is empty or unset} the first time you reference the variable. If empty strings are acceptable and you only care if the variables are set, do ${var?var is unset}. Using ? in the parameter expansion causes the shell to terminate and if the variable is (empty or) unset.
