Basic Commands of
Linux

Evaluating Identity Lifecycle, Privilege Escalation Vectors

• Author: Abdul Wahab (Cyber Security Student)
• Date: August 2026
• Classification: ACADEMIC RESEARCH
• Subject: Users and groups in Linux
• Teacher: farrukh fareed

Directory Navigation Commands

As against the Windows file system which is based on drive letters (C:, D:), the Linux file system is based on one root directory (/). Once you open up your terminal, the very first thing you need to know is your current position in the file system and how you can navigate to other places.This is when we start using the navigation commands, and these are the simplest commands that everyone who uses Linux should know.There is the pwd command (print working directory), which will help us find out the path of the current directory. The second one is ls(list), which will be used for listing the directory content. Again, all options come right after the name of the command, for example, ls -l lists the detailed information of the directory content, while ls -a includes even hidden files.The command for changing directories is cd(change directory).To get into the specific folder, you have to type cd and the name of the folder. To get back, you can use cd .. to go back to the previous directory or cd or cd ~ to get to your user directory.

File and Directory Management Commands

After navigating in the system, the second vital skill set for the user relates to files and directories: creating, copying, moving or renaming, deleting, and other operations. These actions in Linux can be performed by using standard commands. File management commands are very important for day to day operations as well as system administration activities. To create a new blank file, the touch file.txt command will be used. In creating a new folder, it is necessary to use the mkdir Make Directory command. The command to copy files and folders is cp , while the recursive flag has to be set in the command line in order to copy the whole directory (cp -r). The command to rename or move a file is mv. Below are several commands which can be utilized to manipulate, remove, copy or move files and directories. To delete or remove files and directories, the command rm is used. To delete an empty folder, one has to use rmdir command, while to delete a folder with files, the rm -r command works. It is possible to view the content of a file with the help of the cat command and the less command displays the content of the file on the terminal screen. The more command lets the user view the contents of the file one screen at a time.

System Monitoring and Process Management

“Once you have grasped the basics, it is vital that you can monitor system performance and processes running on it. Processes running on the Linux operating system are called ‘Processes’ and every process has its own Process ID. It is necessary for a system administrator to know how much memory or processor is being used by each process. To see what processes are running, one can use the command ‘ps -aux’ (Process Status), which lists all running processes along with their specifications.Sometimes there is a need to watch the processes in real-time, in which case ‘top’ or ‘htop’ Interactive process viewer commands can be used. If there is a process that has frozen, it can be killed by using a kill command with PID as an argument (kill 1234). If the process can not be killed, the kill -9 PID command will do the trick. ‘df -h’ command will show the amount of used and free space on disk, and ‘free -m’ command is used to view Memory utilization.

Networking, Searching, and Advanced Utilities

The Linux command line makes everyday tasks like ping, remote access, or just finding some needed information much easier. These commands are necessary for system administrators and security specialists to ensure that all systems respond to their requests properly and allow access to the required data in the system’s storage. “Ping” is used to determine whether the other server is active and will respond to requests. The command-line tool “ip a” (or “ifconfig” for older Linux versions) shows the IP address of the system. To establish a secure connection with a remote server, you can use the command ssh user@hostname , also known as Secure Shell. The grep command is used to search files for specific text patterns (e.g., grep “error” logfile.txt). In addition, the find command is used to search the system for files by path or name. Finally, to download files from the Internet through the terminal, one can use utilities such as wget or curl .

File Permissions and Security Management

It is required to add it before any command which needs higher privileges than the current shell session allows. Sudo is used to change system wide settings or install new packages for instance. The following command sudo su or sudo -i is run to open a superuser shell. It should be noted that root account has absolute privileges to do anything with a computer that the operating system allows.Linux is an multi-user operating system with a permission-based concept. For each file and directory in the system there are set of permissions defining who can read (r), write (w), execute (x) them. For Linux there are three different types of permissions: Owner, Groups and Others.