Essential Linux Command Cheat Sheet: 50 Must‑Know Commands for System Operations

Essential Linux Command Cheat Sheet

1. Where is the file that stores user accounts? /etc/passwd 2. How to delete a non‑empty directory? rm -rf directory_name 3. Command to display the current working directory? pwd 4. Command to create a directory? mkdir 5. Command that shows one page at a time and keys for navigation?

more
Space: next page
B: previous page

6. Command to display the last 10 lines of a file? tail -n 10 filename 7. Command to return to the current user's home directory? cd ~ 8. Command to count the number of lines in a file? wc -l filename 9. Command to test network connectivity? ping 10. Directory where configuration files are stored? /etc 11. Directory for network‑interface configuration files? /etc/sysconfig/network-scripts 12. Command to force recursive deletion of a folder? rm -rf folder_name 13. Command to copy a file? cp -R source_file destination_file 14. Command to create a directory? mkdir directory_name 15. Create a new file, write "Tsinghua University" to it, then append "Computer Science and Technology".

touch file

echo "清华大学" > hello

echo "计算机科学与技术" >> hello

16. Command to view a file's content?

cat filename
more filename

17. Command to display the current system time? date 18. Command to reboot the system? reboot 19. Command to shut down the system?

halt -p
shutdown now

20. Difference between /sbin and /bin directories?

/bin contains essential system commands usable by all users, including root.

/sbin holds system‑admin commands ("s" for super) that normally require root privileges.

21. Home directory of the root user? /root 22. Meaning of cd .. in Linux?

It moves up one directory level.

23. Meaning of 2> 1> 2>&1 ?

1 is standard output
2 is error output
> redirects output
2>&1 merges error output into standard output

24. Purpose of the pipe symbol | ?

The pipe passes the output of the command on its left as input to the command on its right.

25. Command to create 100 files at once? touch file{1..100} 26. Find directories containing "bin" under the root directory? ls -l | grep bin 27. How many modes does the vi editor have?

vi has three basic modes: command mode, insert mode, and visual mode.

28. How to enter insert mode in vi? Press i 29. How to enter visual mode in vi? Press v 30. How to copy a line in vi? Press y 31. How to paste in vi? Press p 32. Delete lines 3 through 15 in vi? :3,15d 33. Command to create user zhangsan ? useradd zhangsan 34. Set password for zhangsan to 123456 ? passwd zhangsan123456 35. Command to delete a user? userdel username 36. Command to switch user? su username 37. Home directory of user zhangsan ? /home/zhangsan 38. Meaning of -rwxrwxrwx permissions?

Read, write, and execute permissions for owner, group, and others.

39. Meaning of drwx------ permissions?

Directory with read, write, and execute permissions only for the owner.

40. Change a directory's permissions to allow only the owner full access? chmod 700 directory_name 41. Create group super and add zhangsan to it?

groupadd super
usermod -g super zhangsan

42. As zhangsan , create /test and test1.txt , then change its owner to root:root ? chown root:root test1.txt 43. Command to view help for another command? man command_name 44. How to install software? yum install package_name 45. How to uninstall software? yum remove package_name 46. Purpose of the wget command?

Download files from the network.

47. Command to locate where an executable is installed? whereis command_name 48. Save and exit vi? :wq 49. Exit vi without saving? :q! 50. Command to view the current IP address?

ifconfig -a