Patricio Treviño · 31 August, 2018 · 2 min read

Redirecting streams to the /dev/null sink

Redirects the stdout/stderr (or both) to a special location called /dev/null.

The /dev/null device is a special file (not a directory) and it's typically used as a sink for unwanted output streams of a process, or as a convenient empty file for input streams. This is usually done by redirection.

Why is this important? Well imagine you have a very important process that cannot not be interrupted, redirecting outputs is a good way to avoid unhandled errors.

Syntax

<operation> [n]> /dev/null [options]

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Option	Description
operation	The operation whose output will be redirected.
n	The stream to be redirected (see below).
options	The stream redirection options.

Valid values for [n]: 1, standard out 2, standard error &, both

Example

      
        # no redirection
      
        $ echo 'hello'
      
          hello
      
        # redirects standard error (no error in this case)
      
        $ echo 'hello' 2> /dev/null
      
          hello
      
        # redirects standard out to /dev/null (so no output) 
      
        $ echo 'hello' 1> /dev/null 
      
        # redirects everything to /dev/null (so no output)
      
        $ echo 'hello' &> /dev/null 
      
        # no redirection (causing error)    
      
        $ unlink unexisting-file.sh 
      
          unlink: unexisting-file.sh: No such file or directory
      
        # redirects standard error to /dev/null (so no error)
      
        $ unlink unexisting-file.sh 2> /dev/null
      
        # redirects everything to /dev/null (so no error)
      
        $ unlink unexisting-file.sh &> /dev/null

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References

Null device

	# no redirection
	$ echo 'hello'
	hello

	# redirects standard error (no error in this case)
	$ echo 'hello' 2> /dev/null
	hello

	# redirects standard out to /dev/null (so no output)
	$ echo 'hello' 1> /dev/null

	# redirects everything to /dev/null (so no output)
	$ echo 'hello' &> /dev/null

	# no redirection (causing error)
	$ unlink unexisting-file.sh
	unlink: unexisting-file.sh: No such file or directory

	# redirects standard error to /dev/null (so no error)
	$ unlink unexisting-file.sh 2> /dev/null

	# redirects everything to /dev/null (so no error)
	$ unlink unexisting-file.sh &> /dev/null