How to include custom command options in a bash script with $1 and $2?

Question

I have a script myscript.sh

#!/bin/sh

echo $1 $2

which is used something like ...

./myscript.sh foo bar

which gives me an output of ...

foo bar

but how can i make this script include custom command options? for example ...

./myscript.sh -a foo and corespond to $1

and

./myscript.sh -b bar and corespond to $2

There's a [great Q&A on StackOverflow that covers your options](https://stackoverflow.com/questions/192249/how-do-i-parse-command-line-arguments-in-bash/14203146#14203146) in some detail. — Seamus, May 21 '19 at 01:39
@Seamus now I know where they all get the useless quoting of the case variable and of the `a:bc:`optstring from (but do not care to quote arithm or other var expansions). They're cut&pasting from "great" Q&As. — , May 21 '19 at 09:56

Yurij Goncharuk · Answer 1 · 2019-05-21T08:37:01.340

5

You should to use man 1 bash:

Small example:

#!/bin/bash

while getopts "a:b:" opt      # get options for -a and -b ( ':' - option has an argument )
do
    case $opt in
        a) echo "Option a: $opt, argument: $OPTARG";;
        b) echo "Option b: $opt, argument: $OPTARG";;
    esac
done

edited May 21 '19 at 08:37

answered May 20 '19 at 22:46

Yurij Goncharuk

4,177
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A small example is like a picture, worth a thousand words! – FreeSoftwareServers May 21 '19 at 04:01
Assuming you can read code and it's got comments lol – FreeSoftwareServers May 21 '19 at 04:02
@roaima I've add man page about `getopt` (I hurried with answer) but example was about `getopts`. I omitted `:` also. That`s why I've been downvoted. I think so. Maybe the problem in something else. – Yurij Goncharuk May 21 '19 at 10:40
1

@YurijGoncharuk maybe because [man 1 bash](https://linux.die.net/man/1/bash) is not [man 1 getopts](http://man7.org/linux/man-pages/man1/getopt.1.html) ? That being said, I upvoted you! I also appreciated the man 1 bash link as it would do me very well to read it. So thanks my man! :) – Anonymous May 21 '19 at 11:13

score 4 · Accepted Answer · 2019-05-20T23:14:35.263

Since you are listing bash as the shell used, type:

$ help getopts

Which will print something like:

getopts: getopts optstring name [arg]
Parse option arguments.

Getopts is used by shell procedures to parse positional parameters as options.

OPTSTRING contains the option letters to be recognized; if a letter is followed by a colon, the option is expected to have an argument, which should be separated from it by white space.

Each time it is invoked, getopts will place the next option in the shell variable $name, initializing name if it does not exist, and the index of the next argument to be processed into the shell variable OPTIND. OPTIND is initialized to 1 each time the shell or a shell script is invoked. When an option requires an argument, getopts places that argument into the shell variable OPTARG.

Getopts normally parses the positional parameters ($0 - $9), but if more arguments are given, they are parsed instead.

How to include custom command options in a bash script with $1 and $2?

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