sed - a Stream EDitor

The sed utility reads the specified files, or the standard input if
no files are specified, modifying the input as specified by a list
of commands. The input is then written to the standard output.

Usage: sed [OPTION]... {script-only-if-no-other-script} [input-file]...

  -n, --quiet, --silent
                 suppress automatic printing of pattern space
  -e script, --expression=script
                 add the script to the commands to be executed
  -f script-file, --file=script-file
                 add the contents of script-file to the commands to be executed

If no -e, --expression, -f, or --file option is given, then the first
non-option argument is taken as the sed script to interpret.  All
remaining arguments are names of input files; if no input files are
specified, then the standard input is read.

Examples:

	To remove blank lines in a file:
		sed -e /^$/d filename

	To substitute one pattern for another:
		sed -e "s/old_pattern/new_pattern/" filename