How to run a command in the background and get no output?

I wrote two shell scripts a.sh and b.sh. In a.sh and b.sh I have a infinite for loop and they print some output to the terminal. I want to write another script which calls both a.sh and b.sh but I want the user to regain control of the terminal immediately, instead of having the script run infinitely and I want to hide the output in terminal.

Solution 1:

Use nohup if your background job takes a long time to finish or you just use SecureCRT or something like it login the server.

Redirect the stdout and stderr to /dev/null to ignore the output.

nohup /path/to/your/script.sh > /dev/null 2>&1 &

Solution 2:

Redirect the output to a file like this:

./a.sh > somefile 2>&1 &

This will redirect both stdout and stderr to the same file. If you want to redirect stdout and stderr to two different files use this:

./a.sh > stdoutfile 2> stderrfile &

You can use /dev/null as one or both of the files if you don't care about the stdout and/or stderr.

See bash manpage for details about redirections.

Solution 3:

Sorry this is a bit late but found the ideal solution for somple commands where you don't want any standard or error output (credit where it's due: http://felixmilea.com/2014/12/running-bash-commands-background-properly/)

This redirects output to null and keeps screen clear:

command &>/dev/null &

Solution 4:

Run in a subshell to remove notifications and close STDOUT and STDERR:

(&>/dev/null script.sh &)

Solution 5:

If they are in the same directory as your script that contains:

./a.sh > /dev/null 2>&1 &
./b.sh > /dev/null 2>&1 &

The & at the end is what makes your script run in the background.

The > /dev/null 2>&1 part is not necessary - it redirects the stdout and stderr streams so you don't have to see them on the terminal, which you may want to do for noisy scripts with lots of output.