Mass arguments (operands) at first place in command line argument passing

Question

I use following lines (hope this is best practice if not correct me please) to handle command line options: ``` #!/usr/bin/bash read -r -d '' HELP <&2 for i in "${invalid_options[@]}"; do echo $i >&2 done echo "" >&2 echo "$HELP" >&2 exit 1…

Accepted Answer

`getopts` automatically breaks the while loop as soon as it detects a non-dash parameter (not including the argument given to dash parameters that take arguments). The POSIX standard is to have dashed parameters come first, and then have files. There's also none of this `--` and `+` crap either. It's plain and simple.

However, Linux isn't Unix or POSIX compliant. It's just in the nature of the GNU utilities to be "better" than the standard Unix utilities. More features, more options, and handling things a bit differently.

On Linux, command line parameters can come after files in many GNU utilities.

For example:

```
$ cp -R foo bar
```

Work on my Unix certified Mac OS X and on Linux, However,

```
$ cp foo bar -R
```

Only works on Linux.

If you want `getopts` to work like a lot of Linux utilities, you need to do a wee bit of work.

First, you have to process your arguments yourself, and not depend upon `$OPTIND` to parse them. You also need to verify that you have an argument.

I came up with this as an example of doing what you want.

```
#! /bin/bash

while [[ $* ]]
do
    OPTIND=1
    echo $1
    if [[ $1 =~ ^- ]]
    then
        getopts :a:b:cd parameter
        case $parameter in
            a)  echo "a"
                echo "the value is $OPTARG"
                shift
                ;;
            b)  echo "b"
                echo "the value is $OPTARG"
                shift
                ;;
            c)  echo "c"
                ;;
            d)  echo "d"
                ;;
            *) echo "This is an invalid argument: $parameter"
                ;;
        esac
    else
        other_arguments="$other_arguments $1"
    fi
    shift
done
echo "$other_arguments"
```

I now loop as long as `$*` is set. (Maybe I should use `$@`?) I have to do a `shift` at the end of the loop. I also reset `$OPTIND` to `1` each time because I'm shifting the arguments off myself. `$OPTARG` is still set, but I have to do another `shift` to make sure everything works.

I also have to verify if a argument begins with a dash or not using a regular expression in my `if` statement.

Basic testing shows it works, but I can't say it's error free, but it does give you an idea how you have to handle your program.

There's still plenty of power you're getting from `getopts`, but it does take a bit more work.

Mass arguments (operands) at first place in command line argument passing

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