Features of the Linux Operating System

• Multiprogramming
• Time-sharing
• Multitasking
• Virtual Memory
• Shared Libraries
• POSIX(Portable Operating System for the UNIX environment)- Compliance
• Samba
• Cron Scheduler
• Network Information Service(NIS)
• Data Archival Utilities
• Web Server
• Office suite
• Licensing

Linux Architecture
Three main software components

• Kernel
• Shell
• Linux Utilities and Application Program

Basic Commands in Linux

• To navigate to a new directory, the present working directory or print working directory(pwd) Example:

Forgotten whether youre logged in as root or another user, you can use the (whoami) command.

Navigating the Linux Filesystem

• Changing Directories from the terminal with the command>>(cd)change directories
  Example: how to change to the /etc directory used to store configuration files.
  Example:
  

• To see the contents of a directory, you can use the ls (list) command. The command lists both the files and directories contained in the directory.

• For more information about the files and directories you can the -l switch after ls command.
  Example:
  

Every command, application, or utility has a dedicated help file in Linux.
Example if I needed help using wireless cracking tool, aircrack-ng.
Simply type command>>aircrack-ng --help