redirection in linux

 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.