1. uname

‘uname -a’ returns :

• OS – Linux
• Fully Qualified Domain Name (FQDN)
• Kernel version – 2.6.31…
• 2.6 = major version
• 31= minor version
• 14 = Anything else after the minor version indicates that the kernel was patched by the distributor
• Date and time that the kernel was compiled

2. ifconfig

• lists out all the network interfaces
• useful to check or set the IP of an interface.

3. tty – reveals the current terminal
4. whoami – reveals the currently logged-in user
5. which – reveals where in the search path a program is located

6. echo – prints to the screen

• echo $PATH – dumps the current path to STDOUT
• echo $PWD – dumps the contents of the $PWD variable
• echo $OLDPWD – dumps the most recently visited directory

7. set – prints and optionally sets shell variables
8. clear – clears the screen or terminal
9. reset – resets the screen buffer
10. history – reveals your command history

• !362 – executes the 362th command in our history
• command history is maintained on a per-user basis via:
• ~/.bash_history
• ~ = users’s $HOME directory in the BASH shell

11. pwd – prints the working directory
12. cd – changes directory to desired directory

• ‘cd ‘ with no options changes to the $HOME directory
• ‘cd ~’ changes to the $HOME directory
• ‘cd /’ changes to the root of the file system
• ‘cd Desktop/’ changes us to the relative directory ‘Desktop’
• ‘cd ..’ changes us one-level up in the directory tree
• ‘cd ../..’ changes us two-levels up in the directory tree

13. Arrow keys (up and down) navigates through your command history
14. ls – lists files and directories

• ls / – lists the contents of the ‘/’ mount point
• ls -l – lists the contents of a directory in long format:
• Includes: permissions, links, ownership, size, date, name
• ls -ld /etc – lists properties of the directory ‘/etc’, NOT the contents of ‘/etc’
• ls -ltr – sorts chronologically from older to newer (bottom)
• ls –help – returns possible usage information
• ls -a – reveals hidden files. e.g. ‘.bash_history’
• files or directories prefixed with ‘.’ are hidden. e.g. ‘.bash_history’

15. cat : to retrieve information from a file as in the os version in our case.