How to run a command before a Bash script exits?

Bash

Bash Problem Overview


If a Bash script has set -e, and a command in the script returns an error, how can I do some cleanup before the script exits?

For example:

#!/bin/bash
set -e
mkdir /tmp/foo
# ... do stuff ...
rm -r /tmp/foo

How can I ensure that /tmp/foo is removed, even if one of the commands in ... do stuff ... fails?

Bash Solutions


Solution 1 - Bash

Here's an example of using trap:

#!/bin/bash -e

function cleanup {
  echo "Removing /tmp/foo"
  rm  -r /tmp/foo
}

trap cleanup EXIT
mkdir /tmp/foo
asdffdsa #Fails

Output:

dbrown@luxury:~ $ sh traptest
t: line 9: asdffdsa: command not found
Removing /tmp/foo
dbrown@luxury:~ $

Notice that even though the asdffdsa line failed, the cleanup still was executed.

Solution 2 - Bash

From the bash manpage (concerning builtins):

> trap [-lp] [[arg] sigspec ...]
The command arg is to be read and executed when the shell receives signal(s) sigspec.

So, as indicated in Anon.'s answer, call trap early in the script to set up the handler you desire on ERR.

Solution 3 - Bash

sh version of devguydavid's answer.

#!/bin/sh
set -e
cleanup() {
  echo "Removing /tmp/foo"
  rm  -r /tmp/foo
}
trap cleanup EXIT
mkdir /tmp/foo
asdffdsa #Fails

ref: shellscript.sh

Solution 4 - Bash

From the reference for set:

> -e

> Exit immediately if a simple command (see section 3.2.1 Simple Commands) exits with a non-zero status, unless the command that fails is part of an until or while loop, part of an if statement, part of a && or || list, or if the command's return status is being inverted using !. A trap on ERR, if set, is executed before the shell exits.

(Emphasis mine).

Solution 5 - Bash

I don't know if it matters to you if it's before or after.

You can set a script to run immediately after closing with "trap". and then you can close the terminal.

For Example;

    trap  ./val.sh EXIT  #set command you want to run after close terminal 
	kill -9 $PPID        #kill current terminal

Attributions

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionDavid WoleverView Question on Stackoverflow
Solution 1 - BashdevguydavidView Answer on Stackoverflow
Solution 2 - Bashdmckee --- ex-moderator kittenView Answer on Stackoverflow
Solution 3 - BashSafteverView Answer on Stackoverflow
Solution 4 - BashAnon.View Answer on Stackoverflow
Solution 5 - BashErsin ÖztürkView Answer on Stackoverflow