User Administrationadduser <username>: Create a new user named <username>userdel -r <username>: Delete the user named <username>. The -r option removes the user's home folder located at /home/<username>.lastlog: lists all users and the last time that they logged in.groupadd <groupname>: Create a group called <groupname>useradd -G <groupname1>,<groupname2>... <username>: Add a user named <username> to a group or multiple groups.Permissionschown <username>:<groupname> <file or directory>: Change the owner of at file or directory to <username> and <groupname>.chmod <permissions code> <file or directory>: Change the permissions on a file or directory to that specified."Hardware" Resourcestop: Show the top resource using processesps aux: Show all processesfree: Show information about memory allocationdu <file or folder name>: Show the size of a file or folder, recursive for folders.kill <PID>: Kill a process by its ID. Use kill <PID> -9 to force the kill.EC2 Toolsec2-bundle-vol: use to bundle an AMI for your running instance. Use --help for syntax information.ec2-upload-bundle: use to upload your bundle to Amazon's place for these things. Again, Use --help for syntax information.Package Management / Software Installationapt-get: Oh my goodness its so easy to install anything!dpkg -L <package name>: Show a list of all the files that were installed with the named package. Useful since Linux seems so silly about where everything ends up...Debuggingtail -f <log file>: Real-time display of latest log file changes.find / -name <file or folder name fragment>*: Recursively search for folders and files by partial name from root down.