Nested case in bash script

Question

I have written the following function in a bash script but it is not working. Am I missing something obvious?

main_menu() {
dialog \
    --title "Sim Gateway Infomation Utility" \
    --menu "What do you want to do?" 12 60 5 \
    Summary "View overall summary" \
    Details "View details of a sim bank" \
    Modify "Modify used minutes of a sim" \
    Exit "Exit" \
    2>$tempfile

retval=$?
case retval in
    0)

        choice=`cat $tempfile`
        case $choice in
            Summary) summary;;
            Details) details;;
            Modify) modify;;
            Exit) clean_up;;
        esac
        ;;
    1)
        confirm_exit;;
    255)
        confirm_exit;;
esac

}

Jonathan Leffler · Accepted Answer · 2009-09-25 16:24:46Z

5

This article discusses dialog; I'm not experienced with it.

Your 'case retval in' needs to be 'case $retval in (or 'case "$retval" in).

[@Idelic notes that my original answer was more conservative than necesssary.]

The string 'retval' matches none of the options you list in your outer case statement (use a '*' option to detect the unexpected). The double quotes prevent accidents if $retval ever contained spaces; in general, it is a good idea to use double quotes around the variable in case "$var" in statements (and most other places too). In this particular case, it would not matter; the exit status is always a number. In the 'case "$choice" in' statement, I'd be more comfortable with the quotes around the variable - but you may still be safe (I'd need to read more about dialog to be sure of what it does and whether it ever generates spaces - or nothing even).

edited Sep 25, 2009 at 16:24

answered Sep 25, 2009 at 14:20

Jonathan Leffler

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3 Comments

Morchuboo Over a year ago

Of course! many thanks, its amazing how you can look at a script for ages and miss the most obvious typo! cheers dude!

Idelic Over a year ago

The double quotes are not needed for simple "case $VAR in..." statements. There's at least two cases in which you never need the quotes: simple assignment (FOO=$BAR) and the "case ... in" above.

Jonathan Leffler Over a year ago

@Idelic: interesting - I just checked both Korn and Bourne (from Solaris 10) shells, and for assignments you are correct. I didn't check case. Somewhere in the last twenty-five years (and it was in the dim distant past rather than within living memory) I got burned by some of this. Whether that was older versions of shells, or a misunderstanding, or more complicated stuff with 'eval', I don't now remember - it's sad what old age does to you. I'll reformat the answer a bit to note your comment.

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