What does $? mean in shell?

Question

I have script here and I should convert it to python. But one thing that I dont know.

What does this line means:

 if [ $? != 0 ]
            then
                    echo "$i NOT FOUND!"
                    retval=255
            fi

Need help. Thank you.

see http://tldp.org/LDP/abs/html/internalvariables.html#XSTATVARREF — ymonad, Nov 25 '14 at 01:59

score 1 · Answer 1 · answered Nov 25 '14 at 01:58

1

That is testing the exit status (or return code) of the previous command. A value of non-zero traditionally means error.

answered Nov 25 '14 at 01:58

Elliott Frisch

score 0 · Answer 2 · edited May 23 '17 at 12:25

0

$? is used to find the error code of the last executed command. Try the following in the shell:

ls somebogusfile
echo $?

You will get the error code thrown by the ls command.

edited May 23 '17 at 12:25

Community

answered Nov 25 '14 at 01:59

bogeylicious

If the question is a duplicate of another question that already has an answer, just vote to close it as a dup, don't copy the answer from the other question. – abarnert Nov 25 '14 at 02:01

score 0 · Answer 3 · answered Nov 25 '14 at 01:59

0

It is the exit value of the last command run in the foreground.

man bash. :)

answered Nov 25 '14 at 01:59

Beirdo

3 Answers3