Is there a command-line shortcut for ">/dev/null 2>&1"

Question

It's really annoying to type this whenever I don't want to see a program's output. I'd love to know if there is a shorter way to write:

$ program >/dev/null 2>&1

Generic shell is the best, but other shells would be interesting to know about too, especially bash or dash.

Answer 1

>& /dev/null

Answer 2

You can write a function for this:

function nullify() {
  "$@" >/dev/null 2>&1
}

To use this function:

nullify program arg1 arg2 ...

Of course, you can name the function whatever you want. It can be a single character for example.

By the way, you can use exec to redirect stdout and stderr to /dev/null temporarily. I don't know if this is helpful in your case, but I thought of sharing it.

# Save stdout, stderr to file descriptors 6, 7 respectively.
exec 6>&1 7>&2
# Redirect stdout, stderr to /dev/null
exec 1>/dev/null 2>/dev/null
# Run program.
program arg1 arg2 ...
# Restore stdout, stderr.
exec 1>&6 2>&7

Answer 3

In bash, zsh, and dash:

$ program >&- 2>&-

It may also appear to work in other shells because &- is a bad file descriptor.

Note that this solution closes the file descriptors rather than redirecting them to /dev/null, which could potentially cause programs to abort.

Answer 4

Most shells support aliases. For instance, in my .zshrc I have things like:

alias -g no='2> /dev/null > /dev/null' 

Then I just type

program no

Answer 5

Edit: the (:) or |: based solutions might cause an error because : doesn't read stdin. Though it might not be as bad as closing the file descriptor, as proposed in Zaz's answer.

---

• For bash and bash-compliant shells (zsh...):

  $ program &>/dev/null
  OR
  $ program &> >(:) # Should actually cause error or abortion
  

• For all shells:

  $ program 2>&1 >/dev/null
  OR
  $ program 2>&1|: # Should actually cause error or abortion
  

  $ program 2>&1 > >(:) does not work for dash because it refuses to operate process substitution right of a file substitution.

Explanations:

• 2>&1 redirects stderr (file descriptor 2) to stdout (file descriptor 1).
• | is the regular piping of stdout to the stdin of another command.
• : is a shell builtin which does nothing (it is equivalent to true).
• &> redirects both stdout and stderr outputs to a file.
• >(your-command) is process substitution. It is replaced with a path to a special file, for instance: /proc/self/fd/6. This file is used as input file for the command your-command.

---

Note: A process trying to write to a closed file descriptor will get an EBADF (bad file descriptor) error which is more likely to cause abortion than trying to write to | true. The latter would cause an EPIPE (pipe) error, see Charles Duffy's comment.

Answer 6

It's also worth noting, that often times redirecting output is not really necessary. Many Unix and Linux programs accept a "silent flag", usually -n or -q, that suppresses any output and only returns a value on success or failure.

For example

grep foo bar.txt >/dev/null 2>&1
if [ $? -eq 0 ]; then
     do_something
fi

Can be rewritten as

grep -q foo bar.txt
if [ $? -eq 0 ]; then
     do_something
fi

Answer 7

If /dev/null is too much to type, you could (as root) do something like:

ln -s /dev/null /n

Then you could just do:

program >/n 2>&1

But of course, scripts you write in this way won't be portable to other systems without setting up that symlink first.

Answer 8

Ayman Hourieh's solution works well for one-off invocations of overly chatty programs. But if there's only a small set of commonly called programs for which you want to suppress output, consider silencing them by adding the following to your .bashrc file (or the equivalent, if you use another shell):

CHATTY_PROGRAMS=(okular firefox libreoffice kwrite)
for PROGRAM in "${CHATTY_PROGRAMS[@]}"
do
    printf -v eval_str '%q() { command %q "$@" &>/dev/null; }' "$PROGRAM" "$PROGRAM"
    eval "$eval_str"
done

This way you can continue to invoke programs using their usual names, but their stdout and stderr output will disappear into the bit bucket.

Note also that certain programs allow you to configure how much logging/debugging output they spew. For KDE applications, you can run kdebugdialog and selectively or globally disable debugging output.

Answer 9

Seems to me, that the most portable solution, and best answer, would be a macro on your terminal (PC).

That way, no matter what server you log in to, it will always be there.

If you happen to run Windows, you can get the desired outcome with AHK (google it, it's opensource) in two tiny lines of code. That can translate any string of keys into any other string of keys, in situ.

You type "ugly.sh >>NULL" and it will rewrite it as "ugly.sh 2>&1 > /dev/null" or what not.

Solutions for other platforms are somewhat more difficult. AppleScript can paste in keyboard presses, but can't be triggered that easily.