Exit bash script on error in loop

[Johnny Rosenberg]

2013/9/12 Tony Arnold <tony.arnold at manchester.ac.uk>

> Johnny,
>
> On 12/09/13 19:19, Johnny Rosenberg wrote:
> >
> > I can't make exit work as I thought it would work…
> >
> > #!/bin/bash
> >
> > Title="Error"
> > ERROR="Something bad happened."
> >
> > while [ something ]; do
> >     if [[ something_bad ]]; then
> >         yad --title "${Title}" \
> >             --image=error \
> >             --text "${ERROR}" \
> >             --no-buttons \
> >             --timeout 5 &
> >         exit 1
> >     fi
> > done
> > more_statements
> >
> > # End of code
> >
> > The problem is that even if something_bad happens, more_statements are
> > executed. The yad error messages is displayed as expected, though.
> >
> > (yad is a dialogue, similar to zenity, or even a zenity fork, I think –
> > yad=Yet Another Dialogue)
> >
> > So it seems like only the loop is exited when exit 1 is executed, not
> > the whole script. So how can I exit the whole script if something bad
> > happens inside a loop? I'd prefer a solution that doesn't make it
> > necessary to rewrite the script from scratch…
>
> Odd. The following works for me. I'm on 13.04. Cannot find yad in the
> repositories. Where did you get it from?


I don't remember, but I think I compiled it from source.


> And are you definitely using
> bash for your script?
>

I'm on Ubuntu 12.04 and I didn't change anything like that.


>
> #!/bin/bash
>
> i=4
> while [ "$i" -gt "0" ]; do
>     echo "$i - Hello"
>     if [ "$i" -eq "2" ]; then
>         zenity --error --text "Oh no! i=3"
>         exit 1
>     fi
>     let i=i-1
> done
> echo "Oops!"
>


This one works for me too. I also replaced zenity with yad, and it still
works.

I did some more experiments and I found that it's my pipe to a yad progress
bar that cause the problem. Unfortunately I didn't include it in my
example, but here's another example, which I included in a reply to another
reply:

#!/bin/bash

WaitTime=10
TargetPath="This/path/does/not/exist"

if [ ! -e "${TargetPath}" ]; then
    Time=0
    StartTime=$(date +%s%N)

    while [ ! -e "${TargetPath}" ]; do
        sleep .1
        Time=$(($(date +%s%N)-StartTime))
        if [[ Time -ge WaitTime*10**9 ]]; then
            yad --title "Folder missing" \
                --image=error \
                --text "Your device is not connected." \
                --no-buttons \
                --timeout 5
            exit 1
        fi
        echo "$((Time/10**7/WaitTime))"
        Seconds=$((WaitTime-Time/10**9))
        MM=$((Seconds/60))
        SS=$((Seconds-MM*60))
        echo \#$(printf "%s %d:%02d." "Time to connect your device:" "$MM"
"$SS")
    done | \
    yad --progress \
        --title="Folder missing" \
        --image=time \
        --percentage=0 \
        --auto-close
fi

yad --image="info" \
    --title="Another dialogue" \
    --text="You shouldn't see this dialogue"

# End of code

Remove the yad progress thing and it works. The problem is that I WANT the
progress thing…
So I guess the pipe is the problem here somehow, but how and what to do
about it?


Johnny Rosenberg


>
>
> Regards,
> Tony.
> --
> Tony Arnold,                        Tel: +44 (0) 161 275 6093
> Head of IT Security,                Fax: +44 (0) 705 344 3082
> University of Manchester,           Mob: +44 (0) 773 330 0039
> Manchester M13 9PL.                 Email: tony.arnold at manchester.ac.uk
>
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