Command:   sed - stream editor
Syntax:    sed [-egn] [-f script_file] [edit_script] [file]
Flags:     -e  Accept multiple commands commands on the commands line
           -f  The following argument contains the edit script
           -g  Set the global flag on all substitute commands
           -n  Only output selected lines
Examples:  sed -f script <file      # Run a sed script on file
           sed '/pig/s//hog/g' <file # Replace pig by hog in the file

     Sed is a stream editor.  It takes an edit script  either  from  its
argument  or  a  file,  and  performs an edit session on a named file or
stdin, producing output on stdout.