Bash script error using while and case

Question

first time asking a question here and still learning bash, so bear with me.

I made a main screen using while and case, it was supposed to work but it's not and I don't know where I made a mistake.


while [ $WH!=5 ]
do

echo "Choice menu:"
echo "          1) Option 1"
echo "          2) Option 2"
echo "          3) Option 3"
echo "          4) Option 4"
echo "          5) End script"
echo -n "Choose an option: "
read $OP

case $OP in
        1)
            # code;;

        2)
            # more code;;

        3)
            # more code;;

        4)
            # even more code;;

        5)
            echo "Thank you for testing this script!"
            $WH=5;;
esac
done

No matter what I put in $OP, the script keeps repeating the choice menu until I cancel it. I tried moving while and using $OP as the condition, but nothing seemed to work.

The while condition is incorrect, too (needs spaces around !=) - shellcheck.net will tell you things like that. — Benjamin W.
– Benjamin W., Commented Nov 23, 2016 at 16:52
By the way, have a look at the select statement to build simple menus like this. — Benjamin W.
– Benjamin W., Commented Nov 23, 2016 at 17:07
Replace $WH=5 by WH=5 and !" by "! and read $OP by read OP. — Cyrus
– Cyrus, Commented Nov 23, 2016 at 17:07

Inian · Accepted Answer · 2016-11-23 17:01:20Z

2

You have multiple issues in your script:-

while construct needs to be while [ "$WH" != 5 ]. Remember to double-quote all your shell variables.
The read command should be read OP
The case constructs need to atleast one line with a ending ;;
The final assignment statement should be WH=5 and not $WH=5

Use https://www.shellcheck.net to debug such trivial issues.

answered Nov 23, 2016 at 17:01

Inian

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1 Comment

Gordon Davisson Over a year ago

Some general rules: use $ to get variables' values, not when setting their values; use double-quotes around variable references ("$WH" instead of $WH); and spaces matter a huge amount in shell (e.g. around !=). Oh, and one more: it's best to use lowercase variable names, do avoid conflicts with the variables that have special meaning to the shell and/or other programs (those are all caps).

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