Question

This is my code:

    echo $1  $2
    if [ "Release"!="$2" -a "Debug"!="{$2}" ]; then
        echo "error! the arg of -c must be \"Release\" or \"Debug\" !"
        exit 1
    fi
    XCODECONFIG="$2";

when I input

    ./build.sh a Release

the output is:

    a Release
    error! the arg of -c must be "Release" or "Debug" !

it prints “error! the arg of -c must be “Release” or “Debug” !” why doesn’t go on to XCODECONFIG=”$2″?

Answer 1

There must be spaces around !=:

[ "Release" != "$2" -a "Debug" != "{$2}" ]

When you write your expression without spaces, it is syntaticaly correct, but means other thing. It looks like:

[ STR1 -a STR2 ]

In your case, there are != inside, but that means nothing; that is anyway just strings; each string is evaluated as true, and True -a True will be also evaluated as true.