How can I suppress all output from a command using Bash

Question

I have a Bash script that runs a program with parameters   That program outputs some status  doing this  doing that      There isn t any option for this program to be quiet  How can I prevent the script from displaying anything   I am looking for something like Windows   echo off

User · Answer

An alternative that may fit in some situations is to assign the result of a command to a variable:

$ DUMMY=$( grep root /etc/passwd 2>&1 )
$ echo $?
0
$ DUMMY=$( grep r00t /etc/passwd 2>&1 )
$ echo $?
1

Since Bash and other POSIX commandline interpreters does not consider variable assignments as a command, the present command's return code is respected.

Note: assignement with the typeset or declare keyword is considered as a command, so the evaluated return code in case is the assignement itself and not the command executed in the sub-shell:

$ declare DUMMY=$( grep r00t /etc/passwd 2>&1 )
$ echo $?
0

User · Answer

The following sends standard output to the null device  bit bucket    scriptname  gt  dev null   And if you also want error messages to be sent there  use one of  the first may not work in all shells    scriptname  amp  gt  dev null scriptname  gt  dev null 2 gt  amp 1 scriptname  gt  dev null 2 gt  dev null   And  if you want to record the messages  but not see them  replace  dev null with an actual file  such as   scriptname  amp  gt scriptname out   For completeness  under Windows cmd exe  where  nul  is the equivalent of   dev null    it is   scriptname  gt nul 2 gt nul

User · Answer

In your script you can add the following to the lines that you know are going to give an output   some code 2 gt  gt  dev null   Or else you can also try   some code  gt  gt  dev null

User · Answer

Try      yourcommand      is short for  do nothing        is just your command

User · Answer

Like andynormancx  post  use this  if you re working in an Unix environment    scriptname  gt   dev null   Or you can use this  if you re working in a Windows environment    scriptname  gt  nul

User · Answer

Something like  script  gt   dev null 2 gt  amp 1   This will prevent standard output and error output  redirecting them both to  dev null

User · Answer

Take a look at this example from The Linux Documentation Project      3 6 Sample  stderr and stdout 2 file      This will place every output of a program to a file  This is suitable sometimes for cron entries  if you want a command to pass in absolute silence        rm -f   find   -name core   amp  gt   dev null     That said  you can use this simple redirection    path to command  amp  gt  dev null

[bash] How can I suppress all output from a command using Bash?

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