• One of the most powerful features of the shell is the ability to chain commands together, each taking its input from the previous command's output.

  • This is done using the pipe symbol: |

  • Examples (using the wordcount utility):
    $ cat .bashrc | wc
      7   83   534
    $ echo "Hello World" | wc
      1   2   12

  • Technically this redirects standard output of one command to be the standard input of another.
  • Error messages that are printed to standard error are not redirected with the pipe.