How to exit if a command failed? [duplicate]

Solution 1:

Try:

my_command || { echo 'my_command failed' ; exit 1; }

Four changes:

• Change && to ||
• Use { } in place of ( )
• Introduce ; after exit and
• spaces after { and before }

Since you want to print the message and exit only when the command fails ( exits with non-zero value) you need a || not an &&.

cmd1 && cmd2

will run cmd2 when cmd1 succeeds(exit value 0). Where as

cmd1 || cmd2

will run cmd2 when cmd1 fails(exit value non-zero).

Using ( ) makes the command inside them run in a sub-shell and calling a exit from there causes you to exit the sub-shell and not your original shell, hence execution continues in your original shell.

To overcome this use { }

The last two changes are required by bash.

Solution 2:

The other answers have covered the direct question well, but you may also be interested in using set -e. With that, any command that fails (outside of specific contexts like if tests) will cause the script to abort. For certain scripts, it's very useful.

Solution 3:

If you want that behavior for all commands in your script, just add

set -e 
set -o pipefail

at the beginning of the script. This pair of options tell the bash interpreter to exit whenever a command returns with a non-zero exit code. (For more details about why pipefail is needed, see http://petereisentraut.blogspot.com/2010/11/pipefail.html)

This does not allow you to print an exit message, though.

Solution 4:

Note also, each command's exit status is stored in the shell variable $?, which you can check immediately after running the command. A non-zero status indicates failure:

my_command
if [ $? -eq 0 ]
then
    echo "it worked"
else
    echo "it failed"
fi