15

I am looking for a conditional to avoid users from leaving an input value blank. Any suggestions?

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2 Answers 2

Reset to default
14

No inputs (or even spaces I believe) get entered as empty strings, so check input while the input var is empty:

input=
while [[ $input = "" ]]; do
   read input
done
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2 Comments

This has the (minor) problem of not handling ^D as end-of-input, so it will loop forever if it reads from /dev/null. That can be dealt with if you write it as while read input && [ -z "$input" ]; do :; done.
The loop would stuck if there's no input.
5 
unset input
while [ -z ${input} ]; do
     read input
done
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