File and Directory Operations

1. ls – List directory contents

2. cd – Change directory

3. pwd – Print working directory

4. cp – Copy files or directories

5. mv – Move or rename files or directories

6. rm – Remove files or directories

7. mkdir – Make directories

8. rmdir – Remove empty directories

9. find – Search for files in a directory hierarchy

10. locate – Find files by name (uses a database)

📄 File Viewing and Editing

11. cat – View file contents

12. less – View file one page at a time

13. more – View file page-by-page

14. head – View the first few lines of a file

15. tail – View the last few lines of a file

16. nano – Simple text editor

17. vim – Advanced text editor

18. touch – Create an empty file or update timestamp

🔍 System Monitoring and Performance

19. top – Real-time system monitoring

20. htop – Interactive process viewer (better than top)

21. ps – Show running processes

22. free – Show memory usage

23. df – Show disk space usage

24. du – Estimate file space usage

25. uptime – Show how long the system has been running

26. who – Show who is logged in

⚙️ Package Management (varies by distro)

27. apt – Debian-based package manager (apt install, apt update)

28. yum / dnf – RedHat-based package managers

29. pacman – Arch Linux package manager

🔐 Permissions and Ownership

30. chmod – Change file permissions

31. chown – Change file owner or group

32. umask – Set default permissions

🌐 Networking

33. ping – Check connectivity

34. curl – Transfer data from URLs

35. wget – Download files from the internet

36. netstat – Display network connections (deprecated)

37. ss – Display sockets (replacement for netstat)

38. ifconfig / ip – Show or configure network interfaces

39. nmap – Network scanner

📦 Archiving and Compression

40. tar – Archive files

41. gzip / gunzip – Compress or decompress files

42. zip / unzip – Archive and compress files

🧠 Process and Job Control

43. kill – Send signal to process

44. killall – Kill processes by name

45. bg / fg – Background and foreground jobs

46. jobs – List active jobs

47. nice / renice – Set process priority

🛠️ Miscellaneous

48. alias – Create shortcuts for commands

49. history – Show command history

50. man – View manual pages for commands (man ls, etc.)