Ctrl + A Go to the beginning of the line you are currently typing on
Ctrl + E Go to the end of the line you are currently typing on
Ctrl + L Clears the Screen, similar to the clear command
Ctrl + U Clears the line before the cursor position. If you are at the end of the line, clears the entire line.
Ctrl + H Same as backspace
Ctrl + R Let’s you search through previously used commands
Ctrl + C Kill whatever you are running
Ctrl + D Exit the current shell
Ctrl + Z Puts whatever you are running into a suspended background process. fg restores it.
Ctrl + W Delete the word before the cursor
Ctrl + K Clear the line after the cursor
Ctrl + T Swap the last two characters before the cursor
Esc + T Swap the last two words before the cursor
Alt + F Move cursor forward one word on the current line
Alt + B Move cursor backward one word on the current line
Tab Auto-complete files and folder names

Lets you check whether your internet connection is alive or lost
Example : ping techflock.blogspot.com

Lets you trace packets and find if your connection is broken beyond your ip address. Also can be used to track the number of hops to get to the hostname
Example: traceroute techflock.blogspot.com

Find out your ip address, your network interfaces, transferred and received data information
Example : ifconfig

Find out the dns name resolves to a IP - a way to test your dns server
Example: nslookup techflock.blogspot.com

Does the same as above and provides other dns related information
Example: dig techflock.blogspot.com

Find out all the open ports on your machine
Example: netstat -a

Display all the tcp based established connections on your machine
Example: netstat -nt

Telnet or connect to a machine at the specified port to find out whether that machine/server is working right
Example: telnet techflock.blogspot.com 80