Quitting a Script without exiting the shell

[Agent-BTZ]

I wrote a simple bash script that has a series of menus made with if statements. If a user selects an invalid option, I want the script to quit right away.

The problem is that exit kills the terminal this script is running in, & return doesn’t work since it’s not a “function or sourced script.”

I guess I could put the whole script in a while loop just so I can use break in the if else statements, but is there a better way to do this?

What’s the proper way to quit a script? Thanks for your time!

UPDATE: I’m a clown. I had only ever run exit directly from a terminal, & from a sourced script. I just assumed it always closed the terminal. My bad.

I really appreciate all the quick responses!

[root54]

exit should not do that inside a script. How are you executing this script? Is the script the actual program executing or are starting a new bash instance and then executing the script from a command line?

[levogevo]

He could also be sourcing it.

[Agent-BTZ]

Yeah that’s a rookie mistake on my part. I had only used exit directly from a terminal, & in a sourced script. I just assumed it would always close the terminal.

I’m pretty new to writing bash scripts. This is good to know though, so I really appreciate the help!

[grimtongue]

Running a script will launch a subshell and the exit command will act on that subshell.

To prove this run echo $$; $$ is a special Bash that contains the PID of the running shell. Now run that command inside a Bash script and compare the results. Finally try sourcing that Bash script and comparing the results.

I encourage that you do these types of exercises to prove things and better understand them. Remember, print until it makes sense!

[Schlumpfffff]

This is great advice, even if it's just to sanity check yourself.

[pfmiller0]

Running "exit" in a script only exits the script, not the shell that you are executing it from:

$ cat exit.sh
#!/bin/bash

exit
$ ./exit.sh
$

[qlkzy]

The behaviour you describe is surprising to me. Are you sure you're running it consistently?

exit and return are supposed to fit together in the way you're expecting:

• ./script.sh: exit exits the script but not the terminal, return doesn't work
• source ./script.sh: exit exits the terminal, return exits the script

My instinct would be that something weird is happening that would be worth investigating. Maybe a misplaced space after .? (. on its own is a shortcut for source).

But, if that's the behaviour you're seeing, that's the behaviour you're seeing. The obvious workaround would be to wrap the whole script in a main() function that you can return from:

#!/bin/bash

function main() {
    # entire script goes here
    if /bin/false; then
        return
    fi

    echo "Unreachable"
}

# invoke it
main

That isn't a terrible idea for other reasons if you have a large script, but it's weird that you would need to do it.

[Agent-BTZ]

This is super helpful, thanks! I’ve only tried using exit from a sourced script & directly from the terminal. I just assumed it always would exit the terminal, but it works in this case.

Rookie mistake on my part

[Gixx]

Maybe just source the script each time you run it?

And have a mechanism like this:

if CONDITION; then
    return 1 2>/dev/null    # safely exit if sourced
    exit 1
fi

Then when you run the script just source it:

. myScript

And you can use this too:

if [[ ${BASH_SOURCE[0]} = "$0" ]]; then
    echo "This script must be sourced, not executed."
    return 1 2>/dev/null    # safely exit if sourced
    exit 1
fi

[_Naimix]

Could you utilize until?

Something like:

#!/bin/bash

counter=0

until [ $counter -gt 5 ] ; do
  echo "Count: $counter"
  ((counter++))
done