Send stdout and stderr to /dev/null:

bash Syntax (Toggle Plain Text)

sk@sk:~$ which bash
/bin/bash
sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$

sk@sk:~$ which bash /bin/bash sk@sk:~$ which bash >> /dev/null 2>&1 sk@sk:~$

You can still access the return value which is usually why this is done. Here is an example:

bash Syntax (Toggle Plain Text)

sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$ echo $?
0
sk@sk:~$ which asoija0cjas9cuasc >> /dev/null 2>&1
sk@sk:~$ echo $?
1

sk@sk:~$ which bash >> /dev/null 2>&1 sk@sk:~$ echo $? 0 sk@sk:~$ which asoija0cjas9cuasc >> /dev/null 2>&1 sk@sk:~$ echo $? 1