Trap doesn't exit the loop

Question

I'm trying to do a cleanup using trap command. The safe_cancel function is being called when I hit a Ctrl + C but the script isn't being exited. I have to use Ctrl + Z to suspend the script and then kill.

The foo is another script I have in my PATH which returns an exit 1 if it receives an invalid argument.

What am I lacking or doing wrong in this script?

#!/bin/bash

safe_cancel () {
    echo "Cancelling..."
    # do some cleanup here
    exit 1
}

trap safe_cancel 1

while true; do
    read -p "Choose an option: " someOption < /dev/tty
    foo $someOption
    if [[ $? == 0 ]]
    then
        break
        exit 0
    fi
done

Additional details:

I'm writing this script for a Git hook. Apparently, git hooks aren't exactly expecting a standard in/out so I have to explicitly use /dev/tty

Edit:

When using this as part of a git hook, I'm receiving the error
read: read error: 0: Input/output error
and it's an infinite loop

If you have an IO error reading from the redirected FD, the clear meaning is that you don't have TTY access from that process. `/dev/tty` only works from processes with a controlling TTY. — Charles Duffy, Mar 10 '20 at 13:43
BTW, see [Why is testing "$?" to see if a command succeeded or not, an anti-pattern?](https://stackoverflow.com/q/36313216/14122) — Charles Duffy, Mar 10 '20 at 13:45
If you don't have a controlling TTY, that also would explain why ctrl+c is not delivering a signal (so the script interpreter wouldn't have any way of knowing that you typed it). — Charles Duffy, Mar 10 '20 at 13:53
BTW, consider putting an `|| exit` on your `read` command to make the loop no longer infinite. — Charles Duffy, Mar 10 '20 at 19:06

score 2 · Answer 1 · answered Mar 10 '20 at 14:06

Signal 1 is SIGHUP, which is raised if the terminal goes away, for example because you were connected from a remote machine and your session was interrupted because the network disconnected. When you press Ctrl+C, this sends SIGINT.

trap safe_cancel HUP INT

This may or may not be related to the error you get with Git.

Trap doesn't exit the loop

1 Answers1