How to check if a variable is not empty in bash

Asked Aug 15 '17 at 09:57

Active Aug 15 '17 at 09:57

Viewed 188 times

I know, this question has been asked several times here but due to some reason whatsoever none of the answer mentioned before, didn't seem to work for me.

How can I check if the variable is not empty in bash, I tried the following methods but none of them worked:

if [ -z ${VAR+x} ]; then
    echo "VAR is not set"
    exit 1
fi

if [ -z ${VAR+set} ]; then
    echo "VAR is not set"
    exit 1
fi

if [ -z ${VAR} ]; then
    echo "VAR is not set"
    exit 1
fi

if [ -z ${VAR// } ]; then
    echo "VAR is not set"
    exit 1
fi

Any help will be appreciated.

asked Aug 15 '17 at 09:57

Spaniard89

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What doesn't work with `if [ -z ${VAR} ]` ? – hek2mgl Aug 15 '17 at 09:59
"not set" is different from "empty". See the link above. – P.P Aug 15 '17 at 10:00
@hek2mgl With `[ -z ${VAR} ]` it somehow assumes that the Var is set – Spaniard89 Aug 15 '17 at 10:09
@P.P. Lets assume that I am setting declaring the variable but setting it to an empty string, how will I evaluate then? In the answer it states to use `+set`, I tried it out but that doesn't work either – Spaniard89 Aug 15 '17 at 10:10
`[ -z "${VAR}" ]` is correct. If that doesn't work, then the problem is somewhere else. – hek2mgl Aug 15 '17 at 10:11

How to check if a variable is not empty in bash

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