Diff for "BashFAQ/025"

Anchor(faq25)

How can I access positional parameters after $9?

Use ${10} instead of $10. This works for ["BASH"] and KornShell, but not for older BourneShell implementations. Another way to access arbitrary positional parameters after $9 is to use for, e.g. to get the last parameter:

    for last
    do
        : # nothing
    done

    echo "last argument is: $last"

To get an argument by number, we can use a counter:

    n=12        # This is the number of the argument we are interested in
    i=1
    for arg
    do
        if [ $i -eq $n ]
        then
            argn=$arg
            break
        fi
        i=`expr $i + 1`
    done
    echo "argument number $n is: $argn"

This has the advantage of not "consuming" the arguments. If this is no problem, the shift command discards the first positional arguments:

    shift 11
    echo "the 12th argument is: $1"

Although direct access to any positional argument is possible this way, it's hardly needed. The common way is to use getopts(3) to process command line options (e.g. "-l", or "-o filename"), and then use either for or while to process all arguments in turn. An explanation of how to process command line arguments is available here: http://www.shelldorado.com/goodcoding/cmdargs.html