saw someone write " > /dev/null 2> &1" after commands

I know > /dev/null send it to a blackhole. But why add 2 > &1.

I remembered it might have to do with standard error or something. What does it mean. and what other arguments do people put /dev/null.

The "2>&1" is NOT an argument to /dev/null!

Just as "> /dev/null" redirect standard output to /dev/null, "2> &1" redirect standard error to the same file as standard output (in this case to /dev/null).

So ">/dev/null 2>&1" is added after commands if you are not interested in the output from the command.

/dev/null is a special file that automatically (and efficiently) deletes whatever is written to it.

The “>” operator tells the shell to take the output (known as the standard output stream) of a command, and save it to the given file.

“2>” is another form of this, and means to take the error messages from the command (the standard error stream) and save it to the given file instead.

“&1” is a special file that means “the standard output”. So “2>&1” means to redirect the standard error stream to the standard output, in this case /dev/null which causes the streams to be deleted.

You can also have other variations like “1>&2”, which would take the standard output and redirect it to standard error.

“2>&1 >” also has the short-hand form “&>”, meaning “merge standard output and standard error and redirect to…”

You can also use “>>” instead of “>” meaning to append to a file instead of deleting it (not useful with /dev/null).

Also, none of the above are actually arguments to the program; they are all interpreted by the shell, meaning that they can be used with any program. See for much more detail.