IO Redirection

Overview

• stdin - keyboard
• stout - screen
• stderr - error outputs

Output redirection

  ls -al > listing
  echo "This is a test" >> /var/log/messages

Input redirection

  sort < listing
  sort < listing > sorted_list

Pipes

  ls -l | less # only outputs one screen at a time

  du | sort -nr

  ls -l | wc -l

  tar -tzvf tarfile/tgz | less

Error redirection

  myscript.sh 2> errors # redirects stderr rather than stdout

  myscript.sh > allout.txt 2>&1 # redirects stdout and stderr to file