CODEWITHSUNDEEP
bash
njk2015
njk2015

Reputation: 543

In a bash script what is the difference between ${VAR:-...} and ${VAR:?...}

I'm following this tutorial on transformation of variables.

If I have the following:

echo ${TEST:-test} #TEST is undefined, 'test' is printed and TEST is still undefined.
echo ${FOO:?"some text"} #"some text" is printed and FOO is still undefined.

What is the difference between the ':-' and the ':?' above?

Upvotes: 0

Views: 40

Answers (1)

cdarke
cdarke

Reputation: 44394

These are testing shortcuts:

 echo ${TEST:-test}

If $TEST exists then its value will be used, otherwise the value of $test will be used. If you want TEST to be set then you probably need:

echo ${TEST:=test}

Next one:

echo ${FOO:?"some text"}

If $FOO is set then use its value, else output to stderr the error message "some text" (default is "parameter null or not set").

Upvotes: 1

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