10 Essential Linux Commands Every Sysadmin Should Know

Linux is one of the most popular operating systems for servers and a favorite among system administrators worldwide. As a sysadmin, you need to be familiar with essential Linux commands to manage servers and troubleshoot issues.

In this article, we’ll look at ten essential Linux commands every sysadmin should know, along with their practical applications.

1. ls

The ‘ls’ command lists the contents of a directory. It displays the name of files and folders in the current directory.

Syntax: ls [options] [directory]

Options:
-l: Display detailed information about files
-a: Display all files (including hidden files)
-h: Display file sizes in a human-readable format

Practical Application: The ‘ls’ command can be used to check the contents of a directory, including hidden files. You can use it to verify file permissions, ownership, or identify files that occupy much disk space.

2. pwd

The ‘pwd’ command displays the present working directory. It shows the current directory you’re working in.

Syntax: pwd

Practical Application: You can use the ‘pwd’ command to check your current location or to navigate to a specific directory.

3. cd

The ‘cd’ command changes the current directory. It’s used to navigate between directories.

Syntax: cd [directory]

Practical Application: You can use the ‘cd’ command to move between directories. For example, ‘cd /var/log/’ changes the current directory to ‘/var/log/.’

4. mkdir

The ‘mkdir’ command creates a new directory.

Syntax: mkdir [directory]

Practical Application: You can use the ‘mkdir’ command to create a new directory. For example, ‘mkdir /home/user/documents’ creates a new directory named ‘documents’ in the ‘/home/user/’ directory.

5. rmdir

The ‘rmdir’ command removes an empty directory.

Syntax: rmdir [directory]

Practical Application: You can use the ‘rmdir’ command to delete a directory that doesn’t have any files or subdirectories inside it.

6. touch

The ‘touch’ command creates an empty file or updates the timestamp of an existing file.

Syntax: touch [file]

Practical Application: You can use the ‘touch’ command to create an empty file or to update the modification time of an existing file.

7. cp

The ‘cp’ command copies files and directories.

Syntax: cp [options] source destination

Options:
-r: Copy directories recursively
-v: Verbose output
-p: Preserve file attributes

Practical Application: You can use the ‘cp’ command to copy files and directories between locations. For example, ‘cp /var/log/syslog /home/user/backup/’ copies the ‘syslog’ file to the ‘backup’ directory in the user’s home directory.

8. mv

The ‘mv’ command moves or renames files and directories.

Syntax: mv [options] source destination

Options:
-b: Create a backup of the destination file if it exists
-f: Overwrite the destination file if it exists
-i: Prompt before overwriting the destination file

Practical Application: You can use the ‘mv’ command to move files and directories between locations or to rename them. For example, ‘mv /home/user/documents/myfile.txt /home/user/backup/’ moves the ‘myfile.txt’ file to the ‘backup’ directory in the user’s home directory.

9. rm

The ‘rm’ command removes files or directories.

Syntax: rm [options] file

Options:
-r: Remove directories and their contents
-f: Ignore nonexistent files and do not prompt
-i: Prompt before every removal

Practical Application: You can use the ‘rm’ command to delete files or directories. For example, ‘rm /tmp/myfile.txt’ deletes the ‘myfile.txt’ file from the ‘/tmp’ directory.

10. top

The ‘top’ command shows the system’s current processes and resource usage.

Syntax: top

Practical Application: You can use the ‘top’ command to monitor system performance and identify resource-hungry processes. It shows a real-time display of CPU usage, memory usage, and other system statistics.

Conclusion

These ten Linux commands are the most common and essential commands that every sysadmin should know. They are useful for managing servers, troubleshooting issues, and performing routine tasks. By mastering these commands, sysadmins can become more efficient and proficient in their work.