How can i shorten long multiple checking variable in bash?

Question

i want to check multiple variables in bash but end up too much, is there any way to shorten this

i end up like this

if [[ $1 == -a || $2 == -a || $3 = -a ]] && [[ $1 == -b || $2 == -b || $3 = -b ]] && [[ $1 == -c || $2 == -c || $3 = -c ]] && [ $# -eq 4 ]; then
echo "insert some words"
exit
fi

i've tried this to shorten it but won't work

a=-a
b=-b
c=-c
if [[ ${@:1:3} == $a || ${@:1:3} == $b || ${@:1:3} == $c ]] && [ $# -eq 4 ]; then
echo "insert some words"
exit
fi

is there any way to shorten this? thanks in advance!

You could use [`getopts`](https://www.gnu.org/savannah-checkouts/gnu/bash/manual/bash.html#index-getopts) to do the parameter parsing for you. — Benjamin W., Sep 11 '20 at 13:30
Do the -a,-b.-c options take values, or are they flags? Show how you invoke the program. — glenn jackman, Sep 11 '20 at 13:59
This is also the topic of [BashFAQ #35](http://mywiki.wooledge.org/BashFAQ/035). — Charles Duffy, Sep 11 '20 at 14:15
@glennjackman the options should take multiple values to execute the code if it just had 1 value then it will true which is exit. — Moonbeam, Sep 11 '20 at 14:23

Ivan · Answer 1 · 2020-09-11T14:04:34.013

1

Options with getopts

while getopts ":a:b:c:" opt; do
    case $opt in
        (a) a=$OPTARG;;
        (b) b=$OPTARG;;
        (c) c=$OPTARG;;
    esac
done

echo $a $b $c

Or with just case

while [[ $@ ]]; do
    case $1 in
        (-a) a=$2;;
        (-b) b=$2;;
        (-c) c=$2;;
    esac; shift
done

echo $a $b $c

edited Sep 11 '20 at 14:04

answered Sep 11 '20 at 13:51

Ivan

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1

You would need a colon after `c` in the optstring – glenn jackman Sep 11 '20 at 13:57
1

We have other examples already in the knowledge base that cover this ground, and do it more thoroughly. In [How to Answer](https://stackoverflow.com/help/how-to-answer), see the section *Answer Well-Asked Questions*, and therein the bullet point regarding questions that "have been asked and answered many times before". – Charles Duffy Sep 11 '20 at 14:10
@ivan thank you so much for this.. i will try hopefully this solved my problem – Moonbeam Sep 11 '20 at 14:24

How can i shorten long multiple checking variable in bash?

1 Answers1