Backtrack Very Important Commands!

File Operations

pwd          |     Print Name Of Current/Working Directory
cd             |     Changing The Working Directory
cp             |    Copy Files Or Directory
rm            |      Remove Files And Directory
ls              |      List Of Directory Contents

mkdir       |      Make Directory
cat            |     Concatenate Files And Print On Standard Output
mv            |      Move Files
chmod      |      Change Files Permissions

Know Your System

uname        |     Print System Information
who            |    Show Who Is Logged On
cal              |     Displays Calculator
date           |     Print System Date And Time
df               |     Report File System Disk Space Usage
du              |     Estimate File Space Usage
ps              |      Displays Information Of Current Active Processes
kill            |      Allows To Kills Process
clear               Clear The Terminal Screen
cat /proc/cpuinfo Cpuinfo |  Display CPU Information
cat /proc/meminfo            |    Display Memory Information

Compression

tar      |      To Store And Extract Files From An Archive File Known As Tar File
gzip    |      Compress Or Decompress Named Files

Network

ifconfig    |    To Configure Network Interface
ping         |    Check The Other System Are Reachable From The Host System
wget        |    Download Files From Network
ssh          |    Remote Login Program
ftp           |    Download/Upload Files From/To Remote System
last         |    Displays List Of Last Logged In User
telnet     |    Used To Communicate With Another Host Using THe Telnet Protocol

Searching Files

grep     |    Search Files(s) For Specific Text
find      |    Search For Files In A Directory Hierarchy
locate  |    Find Files By Name

Advanced 

• Whoami Command : It display the user information who is currently logged in. 

Command : whoami

• Uptime Command : Uptime Command is used to from how long the your System has been running , it also tells how many users are running and the load average .

Command : uptime

• Uname command : It displays the system information like OS name , OS type etc .

Commands :
uname : This command only show the OS name.
uname -a : This command show complete info.

• Top command : It shows the real-time system process running on your system.

Command: top
(PRESS Z ON KEYBOARD AND CHANGE COLOUR)

• Free command : free command display the total memory, used memory used memory, shared memory, free memory, buffer memory and cached memory .

Commands :
free : It display info in Kb sizes
free -m : It display info in MB(MegaByte)Blocks
free -m -s number : It display memory info in seconds.

• w command : w command reports how many users are on the system and what process they are running .

Command: w

• Hostname : It display and sets any name into hostname .

Command: hostname

Example : Set the hostname of the system to "www.facebook.com"
Command: hostname www.facebook.com