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Asked: 2026-05-10T20:30:37+00:00

I want to check if a variable has a valid year using a regular

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I want to check if a variable has a valid year using a regular expression. Reading the bash manual I understand I could use the operator =~

Looking at the example below, I would expect to see ‘not OK’ but I see ‘OK’. What am I doing wrong?

i='test' if [ $i=~'200[78]' ] then   echo 'OK' else   echo 'not OK' fi
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  1. It was changed between 3.1 and 3.2:

    This is a terse description of the new features added to bash-3.2 since the release of bash-3.1.

    Quoting the string argument to the [[ command’s =~ operator now forces string matching, as with the other pattern-matching operators.

    So use it without the quotes thus:

    i="test" if [[ $i =~ 200[78] ]] ; then     echo "OK" else     echo "not OK" fi
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