Capture exit code of exit command
Solution 1
If you have a script that runs some program
and looks at the program's exit status (with $?
),
and you want to test that script by doing something
that causes $?
to be set to some known value (e.g., 3
), just do
(exit 3)
The parentheses create a sub-shell.
Then the exit
command causes that sub-shell
to exit with the specified exit status.
Solution 2
exit
is a bash built-in, so you can't exec
it. Per bash's manual:
Bash's exit status is the exit status of the last command executed in the script. If no commands are executed, the exit status is 0.
Putting all this together, I'd say your only option is to store your desired exit status in a variable and then exit $MY_EXIT_STATUS
when appropriate.
Solution 3
You can write a function that returns the status given as argument, or 255
if none given. (I call it ret
as it "returns" its value.)
ret() { return "${1:-255}"; }
and use ret
in place of your call to exit
. This is avoids the inefficiency of creating the sub-shell in the currently accepted answer.
Some measurements.
time bash -c 'for i in {1..10000} ; do (exit 3) ; done ; echo $?'
on my machine takes about 3.5 seconds.
time bash -c 'ret(){ return $1 ; } ; for i in {1..10000} ; do ret 3 ; done ; echo $?'
on my machine takes about 0.051 seconds, 70 times faster. Putting in the default handling still leaves it 60 times faster. Obviously the loop has some overhead. If I change the body of the loop to just be :
or true
then the time is halved to 0.025, a completely empty loop is invalid syntax. Adding ;:
to the loop shows that this minimal command takes 0.007 seconds, so the loop overhead is about 0.018. Subtracting this overhead from the two tests shows that the ret
solution is over 100 times faster.
Obviously this is a synthetic measurement, but things add up. If you make everything 100 times slower than they need to be then you end up with slow systems. 0.0
Solution 4
About exec exit 3
... it would try to run an external command called exit
, but there isn't one, so you get the error. It has to be an external command instead of one built in to the shell, since exec
replaces the shell completely. Which also means that even if you had an external command called exit
, exec exit 3
would not return to continue your shell script, since the shell wouldn't be there any more.
Solution 5
You can do this with Awk:
awk 'BEGIN{exit 9}'
Or Sed:
sed Q9 /proc/stat
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Updated on September 18, 2022Comments
-
Admin almost 2 years
I have this in a bash script:
exit 3; exit_code="$?" if [[ "$exit_code" != "0" ]]; then echo -e "${r2g_magenta}Your r2g process is exiting with code $exit_code.${r2g_no_color}"; exit "$exit_code"; fi
It looks like it will exit right after the exit command, which makes sense. I was wondering is there some simple command that can provide an exit code without exiting right away?
I was going to guess:
exec exit 3
but it gives an error message:
exec: exit: not found
. What can I do? :) -
Admin over 5 yearshmmm what do you think about @G-man's idea?
-
solarshado over 5 yearsMaybe I misunderstood what you're trying to accomplish. If you're just trying to set
$?
(though I'm not really sure why you would), that does seem like a solid answer. If you just want to set it to some unsuccessful value,false
is another option. -
icarus over 5 years@iBug The extra space is not needed.
-
Jerb over 5 yearsI guess you could do
exec bash -c "exit 3"
, but at the moment I can't think of any reason to do that as opposed to justexit 3
. -
ilkkachu over 5 years...or with a shell:
sh -c 'exit 9'
-
user1730706 over 5 years@ilkkachu if youre going to do that you might as well do the
(exit 9)
in the accepted answer -
G-Man Says 'Reinstate Monica' over 5 yearsGood point about the inefficiency of creating the sub-shell. I've read that some shells might be smart enough to optimize the fork out in cases like this, but that bash isn't one of them.
-
Centimane over 5 yearsAlso, for debugging purposes it'd be just as simple to set
exit_code="3"
for testing -
G-Man Says 'Reinstate Monica' over 5 yearsYes, wjandrea pointed that out yesterday.