Bash Scripting with Parameters Multiple Parameter Parsing


Example

To parse lots of parameters, the prefered way of doing this is using a while loop, a case statement, and shift.

shift is used to pop the first parameter in the series, making what used to be $2, now be $1. This is useful for processing arguments one at a time.

#!/bin/bash

# Load the user defined parameters
while [[ $# > 0 ]]
do
        case "$1" in

                -a|--valueA)
                        valA="$2"
                        shift
                        ;;

                -b|--valueB)
                        valB="$2"
                        shift
                        ;;

                --help|*)
                        echo "Usage:"
                        echo "    --valueA \"value\""
                        echo "    --valueB \"value\""
                        echo "    --help"
                        exit 1
                        ;;
        esac
        shift
done

echo "A: $valA"
echo "B: $valB"

Inputs and Outputs

$ ./multipleParams.sh --help
Usage:
    --valueA "value"
    --valueB "value"
    --help

$ ./multipleParams.sh
A: 
B:

$ ./multipleParams.sh --valueB 2
A: 
B: 2

$ ./multipleParams.sh --valueB 2 --valueA "hello world"
A: hello world
B: 2