stderr and stdout

  • 0 – stdin, the standard input stream.
  • 1 – stdout, the standard output stream.
  • 2 – stderr, the standard error stream.

Redirecting output
ls -la > file.out

is equivalent to
ls -la 1> file.out

To redirect stderr
command 2> file.err

Sending both stderr and stdout to separate files
command 2> error.txt 1> output.txt

To suppress error messages in the terminal redirect to /dev/null
command 2> /dev/null

Redirect stderr to the current location of stdout and have error messages sent to the same file as standard output
command > file 2>&1