CheatSheet: Linux Commands for DevOps
Absolutely! As a DevOps professional, it’s vital to be proficient in the Linux command line for effective server management, automation, and troubleshooting. In this comprehensive guide, we’ll cover 50+ essential Linux commands(cheatsheet) with clear explanations and practical examples. This will help you enhance your Linux skills in a straightforward and practical manner.
id- This is used to find out user and group names and numeric ID’s (UID or group ID) of the current user or any other user in the server.
Example:id -u root
2. cd - Change Directory: Navigate to a different directory.
Example:cd /home/user/documents
3. pwd - Print Working Directory: Display the current directory's full path. Example: pwd
4. mkdir - Make Directory: Create a new directory.
Example: mkdir new_folder
5. rm - Remove: Delete files or directories.
Example: rm file.txt
6. cp - Copy: Copy files or directories.
Example: cp file.txt /backup
7. mv - Move: Move files or directories.
Example: mv file.txt /new_location
8. touch - Create Empty File: Create a new empty file.
Example: touch new_file.txt
9. cat - Concatenate and Display: View the content of a file.
Example: cat file.txt
10. nano - Text Editor: Open a text file for editing.
Example: nano file.txt
11. grep - Search Text: Search for text patterns in files.
Example: grep "pattern" file.txt
12. find - Search Files and Directories: Search for files and directories. Example: find /path/to/search -name "file_name"
13. chmod - Change File Permissions: Modify file permissions.
Example: chmod 755 file.sh
14. chown - Change Ownership: Change the owner and group of a file or directory.
Example: chown user:group file.txt
15. ps - Process Status: Display running processes.
Example: ps aux
16. top - Monitor System Activity: Monitor system processes in real-time. Example: top
17. kill - Terminate Processes: Terminate a process using its ID. Also can use pkill to terminate processes based on their name or other attributes.
Example: kill PID
pkill Process_Name
18. wget - Download Files: Download files from the internet.
Example: wget https://example.com/file.zip
19. less - To view the contents of a file one screen at a time, allowing for easy navigation and search within the file. Example: less test.log
20. tar - Archive and Extract: Create or extract compressed archive files. Example: tar -czvf archive.tar.gz folder
21. ssh - Secure Shell: Connect to a remote server securely.
Example: ssh user@remote_host
22. scp - Securely Copy Files: Copy files between local and remote systems using SSH.
Example: scp file.txt user@remote_host:/path
23. rsync - Remote Sync: Synchronize files and directories between systems.
Example: rsync -avz local_folder/ user@remote_host:remote_folder/
24. df - Disk Free Space: Display disk space usage.
Example: df -h
25. du - Disk Usage: Show the size of files and directories.
Example: du -sh /path/to/directory
26. ifconfig - Network Configuration: Display or configure network interfaces (deprecated, use ip).
Example: ifconfig
27. ip - IP Configuration: Manage IP addresses and network settings. Example: ip addr show
28. netstat - Network Statistics: Display network connections and statistics (deprecated, use ss).
Example: netstat -tuln
29. systemctl - System Control: Manage system services using systemd. Example: systemctl start service_name
30. journalctl - Systemd Journal: View system logs using systemd's journal.
Example: journalctl -u service_name
31. free - This command displays the total amount of free space available.
Example: free -m
32. at - Execute Commands Later: Run commands at a specified time. Example: echo "command" | at 15:30
33. ping - Network Connectivity: Check network connectivity to a host. Example: ping google.com
34. traceroute - Trace Route: Trace the route packets take to reach a host. Example: traceroute google.com
35. - Check Website Connectivity: Check if a website is up.
Example: curl -Is https://example.com | head -n 1
36. dig - Domain Information Groper: Retrieve DNS information for a domain.
Example: dig example.com
37. hostname - Display or Set Hostname: Display or change the system's hostname.
Example: hostname
38. who - Display Users: Display currently logged-in users.
Example: who
39. useradd - Add User: Create a new user account.
Example: useradd newuser
40. usermod - Modify User: Modify user account properties.
Example: usermod -aG groupname username
41. passwd - Change Password: Change user password.
Example: passwd username
42. sudo - Superuser Do: Execute commands as the superuser.
Example: sudo command
43. lsof - List Open Files: List open files and processes using them. Example: lsof -i :port
44. nc - Netcat: Networking utility to read and write data across network connections.
Example: echo "Hello" | nc host port
45. scp - Secure Copy Between Hosts: Copy files securely between hosts. Example: scp file.txt user@remote_host:/path
46. sed - Stream Editor: Text manipulation using regex.
Example: sed 's/old/new/g' file.txt
47. awk - Text Processing: Pattern scanning and text processing.
Example: awk '{print $2}' file.txt
48. cut - Text Column Extraction: Extract specific columns from text. Example: cut -d"," -f2 file.csv
49. sort - Sort Lines: Sort lines of text files.
Example: sort file.txt
50. diff - File Comparison: Compare two files and show differences. Example: diff file1.txt file2.txt
51. ls - List Files and Directories: List the contents of a directory.
Example: ls -la
52. history - This command is used to view the previously executed command.
Example: history 10
53. cron - Schedule Tasks: Manage scheduled tasks.
Example: crontab -e
54. ssh-keygen - This command is used to generate a public/private authentication key pair. This process of authentication allows the user to connect remote server without providing a password.
Example: ssh-keygen
55. nslookup - This stands for “Name server Lookup”. This is a tool for checking DNS hostname to Ip or Ip to Hostname. This is very helpful while troubleshooting.
Example: nslookup google.com
56. tr - For translating or deleting characters.
These commands cover a wide range of tasks that are essential for DevOps professionals working with Linux systems. Remember to always refer to the man pages (man command) for more detailed information about each command and its options.
Example:cat crazy.txt | tr "[a-z]" "[A-Z]"
57. tnc - This is “Test Network Connection” command. Mostly used command while troubleshooting. It displays diagnostic information for a connection.
Example:tnc google.com --port 443
58. w - Displays current user.
59. su - Switch User.
Example: su - root
60. ac(All Connections) — Total connect time for all users or specified users.
Example: ac john
61. tail — Displays the last part of a file, commonly used to monitor logs in real-time.
Example: tail monitor.logs
62. head — Displays the first part of a file, often used to quickly see the beginning of a file’s content.
Example: head content.txt
63. ip route — To show or manipulate the IP routing table. Shows clear ip tables rules.
Example: ip rout
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Conclusion
DevOps professionals often rely on a set of essential Linux commands to manage systems, automate tasks, and ensure the smooth operation of infrastructure. These commands are foundational for DevOps tasks and are used in various contexts, from system administration to deployment automation.
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