100 Essential Linux Commands: A Comprehensive Guide

[Chetan_Tiwary_]

User Management

1. useradd: Create a new user account.
2. userdel: Delete a user account.
3. usermod: Modify user account information.
4. passwd: Change a user's password.
5. groupadd: Add a new group.
6. groupdel: Delete a group.
7. groupmod: Modify group information.
8. id: Print user and group information.
9. su: Switch user.
10. sudo: Execute commands with elevated privileges.

File and Directory Management

11. ls: List directory contents.
12. cd: Change directory.
13. pwd: Print working directory.
14. mkdir: Create a directory.
15. rmdir: Remove an empty directory.
16. rm: Remove files or directories.
17. cp: Copy files or directories.
18. mv: Move or rename files and directories.
19. touch: Update file timestamps.
20. chmod: Change file permissions.
21. chown: Change file ownership.
22. chattr: Change file attributes.
23. ln: Create symbolic links.
24. find: Find files based on criteria.
25. locate: Find files using a database.
26. grep: Search for patterns in files.
27. sed: Stream editor for text manipulation.
28. awk: Text processing language.
29. cut: Extract columns from text.
30. paste: Merge lines of text files.
31. sort: Sort lines of text.
32. uniq: Filter out repeated lines.
33. wc: Count words, lines, and characters in a file.
34. diff: Compare files line by line.
35. patch: Apply patches to files.
36. head: Display the first few lines of a file.
37. tail: Display the last few lines of a file.
38. less: View files one page at a time.
39. more: Similar to less, but with fewer features.
40. cat: Concatenate and display files.
41. tac: Concatenate and display files in reverse order.

Text Editing

42. vi/vim: Powerful text editor.
43. nano: Simple text editor.
44. emacs: Advanced text editor.

System Information and Monitoring

45. top: Display system processes.
46. htop: Interactive process viewer.
47. vmstat: Show system memory, processes, interrupts, paging, block I/O, and CPU info.
48. mpstat: Monitor per-processor statistics.
49. iostat: Monitor block I/O statistics.
50. netstat: Show network statistics.
51. ifconfig: Configure network interfaces.
52. ip: Advanced network configuration tool.
53. ss: Show socket statistics.
54. lsof: List open files.
55. free: Display system memory usage.
56. df: Display disk usage.
57. du: Estimate disk space usage.
58. uptime: Show system uptime and load average.
59. date: Display or set system date and time.
60. cal: Display a calendar.

System Administration

61. lspci:  List all PCI devices.
62. lsusb: List USB devices.
63. passwd: Change passwords.
64. systemctl: Control systemd services.
65. journalctl: View systemd journal logs.
66. crontab: Schedule tasks to run periodically.
67. at: Schedule one-time commands to run at a specific time.
68. dmesg: Print kernel ring buffer.
69. mkfs: Create a filesystem.
70. fsck: Check and repair a filesystem.
71. mount: Mount a filesystem.
72. umount: Unmount a filesystem.
73. fdisk: Partition disk drives.
74. parted: Partition disk drives (more advanced).
75. blkid: Print block device information.
76. dd: Copy and convert files.
77. tar: Archive and compress files.
78. gzip/gunzip: Compress and decompress files.
79. bzip2/bunzip2: Another compression utility.
80. xz/unxz: Another compression utility.
81. zip/unzip: Zip and unzip files.
82. unrar: Extract RAR archives.
83. 7z: 7-Zip file archiver.
84. screen: Terminal multiplexer.
85. tmux: Terminal multiplexer.
86. nohup: Run commands in the background.
87. nice/renice: Change process priority.
88. sleep: Pause execution for a specified time.
89. wait: Wait for background jobs to finish.
90. kill: Send signals to processes.
91. killall: Kill all processes matching a name.
92. pkill: Kill processes based on a pattern.
93. bg: Send a job to the background.
94. fg: Bring a job to the foreground.
95. jobs: List background jobs.
96. nc: Netcat, a network utility for reading from and writing to network connections.
97. ping: Check network connectivity.
98. traceroute: Trace the route packets take to a destination.
99. nslookup: Query Domain Name System (DNS) servers.
100. dig: DNS lookup utility.

[Leon120]

Thank You

[Chetan_Tiwary_]

Adding 30 advanced but useful Linux commands to this popular cheat sheet :

1. xargs – Build and execute commands from standard input (eg: pipe find results into other commands).
   
   
2. watch – Run a command repeatedly and display its changing output over time.
   
   
3. alias – Create a shortcut for a longer command.
   
   
4. unalias – Remove a previously defined alias.
   
   
5. whereis – Locate the binary, source and manual page for a command.
   
   
6. strace – Trace system calls and signals used by a process (good for debugging).
   
   
7. jq – Process JSON data on the command line.
   
   
8. tcpdump – Capture and display network packets for troubleshooting network issues.
   
   
9. iftop – Monitor real-time bandwidth usage per interface/host.
   
   
10. rsync – Sync files/directories locally or over network (efficient for backups).
    
    
11. umask – Set default file creation permissions for new files/directories.
    
    
12. chroot – Change the root directory for a process (useful for rescue & isolation).
    
    
13. trap – Define shell script actions when signals are received (for cleanup, etc).
    
    
14. tee – Read from standard input and write to standard output and to files.
    
    
15. disown – Remove a job from shell’s job-control so it won’t receive SIGHUP after logout.
    
    
16. env – Run a command in a modified environment or display environment variables.
    
    
17. export – Set environment variables for current session or children processes.
    
    
18. unset – Remove environment variables from current shell.
    
    
19. sysctl – Modify kernel parameters at runtime.
    
    
20. xfs_growfs / resize2fs / lvextend – Expand filesystems or LVM volumes online (depending on file system type).
    
    
21. lsof +D <dir> – List open files under a directory tree (helps find what’s blocking unmount, etc).
    
    
22. ncdu – Interactive disk usage explorer (useful on head-less servers).
    
    
23. vgdisplay / pvdisplay / lvdisplay – Display LVM volume group / physical volume / logical volume details.
    
    
24. ss -tunlp – Show listening sockets with process names (modern replacement/enhancement for netstat).
    
    
25. nmcli – Command-line tool to manage network settings via NetworkManager.
    
    
26. hdparm – Show or set SATA/IDE drive parameters (for hardware/IO tuning).
    
    
27. smartctl – Monitor SMART status of drives (for early detection of disk failure).
    
    
28. pgrep: Pattern match to find process IDs
    
    
29. apropos – Search the manual page names & descriptions for keywords.
    
30. ipcrm – Remove System V interprocess communication objects (shared memory, message queues, semaphores).

[Blue_bird]

Great Information..!

Thanks for sharing..! @Chetan_Tiwary_ 

[Chetan_Tiwary_]

glad that it is useful @Blue_bird !

[DamianB]

The most useful Linux commands from my career as a CAE engineer.
On HPC and local machines. Master these (and their combinations), and you can work miracles:
find, grep, xargs, awk, sed, cat, crontab