How do I suppress shell script error messages?

Question

In my shell script I got these lines:

rm tempfl.txt
rm tempfl2.txt

If these do not exist I get the error messages:

rm: tempfl2.txt: No such file or directory
rm: tempfl.txt: No such file or directory

Is there a way to only suppress these messages even though they do not always appear, as the files might exist?

Rations

Have a look here: #12786033 – Describe

Answer 1

You have two options:

Suppress rm warnings

$ rm tempfl.txt 2> /dev/null

Redirect script output to /dev/null

$ ./myscript.sh 2> /dev/null

The latter has a drawback of missing all other warning messages produced by your script.

Ashcroft

rm -f should be used carefully. – Gnosis

Answer 2

As the other answers state, you can use command 2> /dev/null to throw away the error output from command

But what is going on here?

> is the operator used to redirect output. 2 is a reference to the standard error output stream, i.e. 2> = redirect error output.

/dev/null is the 'null device' which just swallows any input provided to it. You can combine the two to effectively throw away output from a command.

Full reference:

• > /dev/null throw away stdout
• 1> /dev/null throw away stdout
• 2> /dev/null throw away stderr
• &> /dev/null throw away both stdout and stderr

Eichelberger

Thanks. This is the first place I've seen fully explain what the different parts of 2&>1 actually mean. – Brilliancy

@Brilliancy So what does 2&>1 do? Isn't the 2 redundant here? – Alysiaalyson

Please resist using &>/dev/null which appears to be a shorthand of > /dev/null 2>&1! It might not be harmful in Bash, but to clear things up: It's not POSIX compliant and always produces an exit code of 0, when using #!/usr/bin/env sh as a shebang on some systems. It's a better habit to use > /dev/null 2>&1 instead. I had to learn it the hard way. – Partition

Answer 3

We can use 2> /dev/null to suppress the output error and || true to ensure a success exit status:

rm foo
=> rm: cannot remove ‘foo’: No such file or directory

rm foo 2> /dev/null
echo $?
=> 1

rm foo 2> /dev/null || true
echo $?
=> 0

If you are using the command in a shell script, makefile, etc, maybe you need this.

Slicer

Answer 4

you should redirect all error message to /dev/null like

rm tempfl2.txt 2> /dev/null

Otha

Answer 5

Adding to the answers above: It is probably a better idea to keep error messages (like permission denied or some such). Just test existence of the file before deleting it:

[ -f file.txt ] && rm file.txt

This assumes a Bourne like shell, e.g., bash. The above has the additional benefit that it won't try to delete a directory, something rm can't do.

Polarization

This is obviously prone to error in scenarios where something else removes the file between the time you check and the time you attempt to remove it. rm -f file.txt is atomic and will simply no-op if the file doesn't exist. – Rhodonite

Answer 6

Try this command:

rm -f tempfl.txt

the -f option acts like this:

-f, --force  ignore nonexistent files, never prompt

The command also doesn't report a non-zero error code in case the file doesn't exist.

Thrive

Could you give more of an explanation for your answer? – Kino