COMMAND_OUTPUT >
      # Redirect stdout to a file.
      # Creates the file if not present, otherwise overwrites it.

      ls -lR > dir-tree.list
      # Creates a file containing a listing of the directory tree.

   : > filename
      # The > truncates file "filename" to zero length.
      # If file not present, creates zero-length file (same effect as 'touch').
      # The : serves as a dummy placeholder, producing no output.

   > filename    
      # The > truncates file "filename" to zero length.
      # If file not present, creates zero-length file (same effect as 'touch').
      # (Same result as ": >", above, but this does not work with some shells.)

   COMMAND_OUTPUT >>
      # Redirect stdout to a file.
      # Creates the file if not present, otherwise appends to it.


      # Single-line redirection commands (affect only the line they are on):
      # --------------------------------------------------------------------

   1>filename
      # Redirect stdout to file "filename."
   1>>filename
      # Redirect and append stdout to file "filename."
   2>filename
      # Redirect stderr to file "filename."
   2>>filename
      # Redirect and append stderr to file "filename."
   &>filename
      # Redirect both stdout and stderr to file "filename."
      # This operator is now functional, as of Bash 4, final release.

   M>N
     # "M" is a file descriptor, which defaults to 1, if not explicitly set.
     # "N" is a filename.
     # File descriptor "M" is redirect to file "N."
   M>&N
     # "M" is a file descriptor, which defaults to 1, if not set.


   2>&1
      # Redirects stderr to stdout.
      # Error messages get sent to same place as standard output.
        >>filename 2>&1
            bad_command >>filename 2>&1
            # Appends both stdout and stderr to the file "filename" ...
        2>&1 | [command(s)]
            bad_command 2>&1 | awk '{print $5}'   # found
            # Sends stderr through a pipe.
            # |& was added to Bash 4 as an abbreviation for 2>&1 |.

   i>&j
      # Redirects file descriptor i to j.
      # All output of file pointed to by i gets sent to file pointed to by j.

   >&j
      # Redirects, by default, file descriptor 1 (stdout) to j.
      # All stdout gets sent to file pointed to by j.