How to hide the output of a shell application in Linux?

Question

How to hide the screen output (printf) of a shell application in Linux?

Answer 1

You can redirect the output of any program so that it won't be seen.

$ program > /dev/null

This will redirect the standard output - you'll still see any errors

$ program &> /dev/null

This will redirect all output, including errors.

Answer 2

There are three IO devices available on the commandline.

 standard in - 0 
 standard out - 1 
 standard error - 2

To redirect standard out (the default output) to a file (and overwrite the file), use

 command > file.log

To append to file.log, use 2 >s

 command >> file.log

to redirect standard error to the file.log, use

 command 2> file.log

and to append

 command 2>> file.log

To combine the outputs into one stream and send them all to one place

 command > file.log 2>&1

This sends 2 (stderr) into 1 (stdout), and sends stdout to file.log

Notice that it's also possible to redirect standard in into a command that expects stdin

 command << file.txt

EDIT
For more details, check out the Advanced Bash Scripting Guide

Answer 3

For Mac OS X (10.6 "Snow Leopard"):

If you need to hide the output without letting the program know it by checking the output/error file descriptor you can try using the following in a shell:

stty flusho; command ;stty -flusho

or if you just want to hide input from the terminal by the way:

stty  -echo; command ;stty  echo

See stty(1) manual page for more information

For Linux all i know is that Ubunutu (10.04 "Lucid") and some "Debian/Arch" (commented below - tnx hendry) doesn't have the flusho setting (and i can't see anything other appropriate in the man-page). The echo setting works on the Ubuntu anyway.

Answer 4

If you just want to hide the output (and not save it to a file), you can use:

Edited:

$ command &> /dev/null