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Shell Function: Compare Output of Two Commands

I just wrote this up for some test automation. This function gets passed two commands, runs both commands, and returns “PASS” if they match, or “FAIL” with the diff if they do not match.

compare_output()
{
    out1=/tmp/output-$$.1
    out2=/tmp/output-$$.2
    $1 2>&1 > $out1
    $2 2>&1 > $out2
    diff -q >/dev/null $out1 $out2
    if [ $? != 0 ]; then
        echo "FAIL"
        echo
        echo "Details:"
        diff $out1 $out2
        echo
    else
        echo "PASS"
    fi
    rm $out1 $out2
}

echo -n "Test that will fail: "
compare_output 'echo pass' 'echo fail'

echo -n "Text that will pass: "
compare_output 'echo pass' 'echo pass'