第109页 | Learning the Bash Shell | 阅读 ‧ 电子书库

Options with Arguments

We need to add one more ingredient to make option processing really useful. Recall that many commands have options that take their own arguments. For example, the cut command, on which we relied heavily in Chapter 4, accepts the option -d with an argument that determines the field delimiter (if it is not the default TAB). To handle this type of option, we just use another shift when we are processing the option.

Assume that, in our alice script, the option -b requires its own argument. Here is the modified code that will process it:

while [ -n "$(echo $1 | grep '-')" ]; do
    case $1 in
        -a ) process option -a ;;
        -b ) process option -b 
               $2 is the option's argument
             shift ;;
        -c ) process option -c ;;
        *  ) echo 'usage: alice [-a] [-b barg] [-c] args...'
             exit 1
    esac
    shift
done
    
normal processing of arguments...