Bash: run command2 if command1 fails

Question

I want to do something like this:

if cmd1 && cmd2
echo success
else
echo epic fail
fi

How should I do it?

You're just missing the "then" keyword before the "echo success" command. — glenn jackman, Jun 22 '11 at 10:29
Hmmm; your pseudocode seems to ask a different question than the one in your title..... — mattdm, Jun 22 '11 at 14:43
Good resource for some shell scripting exit conditions http://www.pixelbeat.org/programming/shell_script_mistakes.html — Flashman, Jun 22 '11 at 15:16

score 133 · Accepted Answer · answered Jun 22 '11 at 09:36

133

These should do what you need:

cmd1 && cmd2 && echo success || echo epic fail

or

if cmd1 && cmd2; then
    echo success
else
    echo epic fail
fi

answered Jun 22 '11 at 09:36

Petr Uzel

4

This works, but I'm confused why `||` doesn't look at the output of the first `echo` command. – mlissner Aug 19 '15 at 21:32
1

@mlissner, the if else expects to exit codes, 0 if the command where launched and 1 if where errors. Do not read at the output. `Just try whoami && whoami && echo success || echo epic fail` and now `whoami && whoareyou && echo success || echo epic fail`. I cant figure out what you mean by "doesn't look at the output of the first echo command" – m3nda Feb 09 '16 at 14:41
1

@mlissner I think I got your question, but the answer is that echo command won't fail ever. That is, its return will be 0, i.e. truthy. So the condition that really matters is just `cmd1 && cmd2` – Kazim Zaidi Aug 23 '17 at 11:25
`printf "$(( 1/0 ))" || echo "failed"` does not work. However, putting `printf "$(( 1/0 ))"` in step_1.sh, then running `./step_1.sh || echo "failed"` behaves as expected. – Wassadamo Aug 23 '22 at 05:29

Orlando Rivera Letelier · Answer 2 · 2019-09-04T16:26:30.863

The pseudo-code in the question does not correspond to the title of the question.

If anybody needs to actually know how to run command 2 if command 1 fails, this is a simple explanation:

cmd1 || cmd2: This will run cmd1, and in case of failure it will run cmd2
cmd1 && cmd2: This will run cmd1, and in case of success it will run cmd2
cmd1 ; cmd2: This will run cmd1, and then it will run cmd2, independent of the failure or success of running cmd1.

score 32 · Answer 3 · edited Apr 13 '17 at 12:36

Petr Uzel is spot on but you can also play with the magic $?.

$? holds the exit code from the last command executed, and if you use this you can write your scripts quite flexible.

This questions touches this topic a little bit, Best practice to use $? in bash? .

cmd1 
if [ "$?" -eq "0" ]
then
  echo "ok"
else
  echo "Fail"
fi

Then you also can react to different exit codes and do different things if you like.

3 Answers3