Get numeric return value from command

Question

In a bash shell if a command is successful it returns 0, and if unsuccessful it returns a another number. How do I get the number returned?

For example, I want the return code number returned from the ls command

I try:

echo $ls
echo $(ls)
echo $(?ls)

But none give me what I am looking for. Any tips?

Chris Hayes · Accepted Answer · 2013-11-17 19:09:32Z

5

After running a command, the $? variable will contain the command's exit code.

# This prints 0..
ls; echo $?

# .. and this prints 1
(exit 1); echo $?

answered Nov 17, 2013 at 19:09

Chris Hayes

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2 Comments

The variable is called ?, placing the $ operator on the LHS gives the value.

Fair point, thanks. Worth noting is that it's not assignable like other variables (at least not through any basic testing I tried).

Arkku · Accepted Answer · 2013-11-17 19:16:49Z

2

The special variable $? contains the previous command's return status.

For example:

ls
echo $?
false
echo $?

Note that if you run another command before checking $?, its value will be that of the new command:

false
echo $? # prints the return status of false
echo $? # now prints the return status of the previous echo

So if you wish to use the status more than once, save it to a variable (e.g., err=$?).

answered Nov 17, 2013 at 19:11

Arkku

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The special variable is called ?, placing the $ operator on the LHS gives the value.

@cdarke True, but in the context I think it's clearer to say $?.