How can I hide the output of a shell application in Linux?

Question

How can I 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 I/O devices available on the command line.

 standard input  - 0
 standard output - 1
 standard error  - 2

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

 command > file.log

To append to file.log, use two >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 (standard error) into 1 (standard output), and sends standard output to file.log

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

 command << file.txt

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

Answer 3

Hide standard output:

./command >/dev/null

Hide standard and error outputs:

./command >/dev/null 2>&1

Hide standard output and error outputs and release the terminal (run the command in the background):

./command >/dev/null 2>&1 &

Answer 4

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

Edited:

$ command &> /dev/null

Answer 5

For Mac OS X v10.6 (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 Ubuntu 10.04 (Lucid Lynx) and some Debian/Arch Linux (commented below - thanks, 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.