### Command Chaining ###

 1. Permits the execution of multiple commands in sequence
 2. Also permits execution based on the success or failure of a previous command
 1. cat 123.txt ; ls -l - this runs first command, then second command without regards for exit status of the first command
 2. cat 123.txt && ls -l - this runs second command, if first command is successful
 3. cat 1234.txt && ls -l
 4. cat 123.txt || ls -l - this runs second command, if first command fails

24. more|less - paginators, which display text one-page @ a time
 1. more /etc/fstab
 2. less 1thousand.txt
25. seq - echoes a sequence of numbers
 a. seq 1000 > 1thousand.txt - creates a file with numbers 1-1000
26. su - switches users
 a. su - with no options attempts to log in as 'root'
27. head - displays opening lines of text files
 a. head /var/log/messages
28. tail - displays the closing lines of text files
 a. tail /var/log/messages
29. wc - counts words and optionally lines of text files
 a. wc -l /var/log/messages
 b. wc -l 123.txt
30. file - determines file type
 a. file /var/log/messages