UNIX for Dummies Questions & Answers

Single brackets are a synonym for test - which is a Unix command.

Both syntaxes are available in most unix Bourne-type shells.

The [[ ]] syntax is a "Conditional Expression" and is described in that section in the manual for your Shell. This uses && for "and" and || for "or". Many shells won't do more than one "and" or "or" condition in any one expression.

The [ ] syntax is a "Test" and is partially described in the manual for your Shell and explained further in "man test". There you will find -a for "and" and -o for "or".

Personally in your script I'd use "case" !

Code:

CHECK=M10;
case "${CHECK}" in
"M9"|"M10"|"M11"|"M12")
        echo "hello hi"
        ;;
*)
        echo "how are u hello hi"
        ;;
esac