LINUX

LINUX COMMANDS

1. ls: A command for listing the contents of a directory. Example usage: ls /home/user

2. cd: A command for changing the current working directory. Example usage: cd /home/user/Documents

3. pwd: A command for printing the current working directory. Example usage: pwd

4. mkdir: A command for creating a new directory. Example usage: mkdir new_directory

5. rm: A command for deleting files and directories. Example usage: rm file.txt

6. cp: A command for copying files and directories. Example usage: cp file.txt /home/user/Documents

7. mv: A command for moving or renaming files and directories. Example usage: mv file.txt new_name.txt

8. cat: A command for displaying the contents of a file. Example usage: cat file.txt

9. less: A command for displaying the contents of a file in a scrollable view. Example usage: less file.txt

10. head: A command for displaying the first lines of a file. Example usage: head file.txt

11. tail: A command for displaying the last lines of a file. Example usage: tail file.txt

12. grep: A command for searching for a specific pattern in a file. Example usage: grep pattern file.txt

13. find: A command for searching for files or directories. Example usage: find /home/user -name file.txt

14. chmod: A command for changing the permissions of a file or directory. Example usage: chmod 755 file.txt

15. chown: A command for changing the owner of a file or directory. Example usage: chown user:group file.txt

16. ssh: A command for connecting to a remote host over SSH. Example usage: ssh user@host

17. scp: A command for copying files between local and remote hosts over SSH. Example usage: scp file.txt user@host:/path/to/destination

18. tar: A command for creating and manipulating archive files. Example usage: tar -cvf archive.tar file1 file2

19. gzip: A command for compressing and decompressing files. Example usage: gzip file.txt

20. top: A command for monitoring system processes and resource usage. Example usage: top

21. ps: A command for displaying information about running processes. Example usage: ps aux

22. kill: A command for terminating a process. Example usage: kill PID

23. df: A command for displaying disk usage. Example usage: df -h

24. du: A command for displaying the size of files and directories. Example usage: du -sh /path/to/directory

25. apt-get: A command for managing packages on Debian-based Linux distributions. Example usage: sudo apt-get update

26. yum: A command for managing packages on Red Hat-based Linux distributions. Example usage: sudo yum update

27. ping: A command for testing network connectivity. Example usage: ping google.com

28. traceroute: A command for tracing the route of network packets. Example usage: traceroute google.com

29. ifconfig: A command for displaying and configuring network interfaces. Example usage: ifconfig

30. ip: A command for displaying and configuring network interfaces, routes, and addresses. Example usage: ip addr show

31. whoami: A command for displaying the current user. Example usage: whoami

32. sudo: A command for executing a command with elevated privileges. Example usage: sudo apt-get update

33. useradd: A command for creating a new user account. Example usage: sudo useradd -m newuser

34. usermod: A command for modifying user account attributes. Example usage: sudo usermod -aG sudo newuser

35. passwd: A command for changing the password of a user account. Example usage: passwd newuser

36. history: A command for displaying the command history. Example usage: history

37. alias: A command for creating and displaying command aliases. Example usage: alias ll='ls -alF'

38. date: A command for displaying the current date and time. Example usage: date

39. cal: A command for displaying a calendar. Example usage: cal

40. who: A command for displaying the users currently logged in. Example usage: who

41. uptime: A command for displaying the system uptime. Example usage: uptime

42. hostname: A command for displaying the hostname of the system. Example usage: hostname

43. df: A command for displaying disk space usage. Example usage: df -h

44. free: A command for displaying the amount of free memory. Example usage: free -h

45. mount: A command for mounting a file system. Example usage: sudo mount /dev/sdb1 /mnt

46. umount: A command for unmounting a file system. Example usage: sudo umount /mnt

47. chroot: A command for changing the root directory. Example usage: sudo chroot /mnt

48. ln: A command for creating links between files. Example usage: ln -s /path/to/file /path/to/link

49. lsof: A command for displaying information about open files. Example usage: sudo lsof /path/to/file

50. ssh-keygen: A command for generating SSH keys. Example usage: ssh-keygen -t rsa -b 4096 -C "user@host"

51. ssh: A command for connecting to a remote server over SSH. Example usage: ssh user@host

52. scp: A command for securely copying files between hosts. Example usage: scp /path/to/file user@host:/path/to/destination

53. rsync: A command for efficiently synchronizing files between hosts. Example usage: rsync -avz /path/to/source user@host:/path/to/destination

54. ps: A command for displaying information about running processes. Example usage: ps aux

55. top: A command for displaying information about the top CPU-consuming processes. Example usage: top

56. kill: A command for terminating a process. Example usage: kill 1234

57. pkill: A command for terminating a process by name. Example usage: pkill firefox

58. jobs: A command for displaying a list of background jobs. Example usage: jobs

59. bg: A command for running a job in the background. Example usage: bg %1

60. fg: A command for bringing a job to the foreground. Example usage: fg %1

61. cron: A command for scheduling jobs to run at specified intervals. Example usage: crontab -e

62. at: A command for scheduling a job to run at a specified time. Example usage: at now + 1 hour

63. curl: A command for transferring data from or to a server. Example usage: curl https://example.com

64. wget: A command for downloading files from the web. Example usage: wget https://example.com/file

65. ping: A command for testing network connectivity. Example usage: ping 8.8.8.8

66. traceroute: A command for displaying the path packets take to a destination. Example usage: traceroute google.com

67. route: A command for displaying and modifying the system routing table. Example usage: sudo route add default gw 192.168.0.1

68. ifconfig: A command for displaying network interface information. Example usage: ifconfig

69. ip: A command for displaying and modifying IP address information. Example usage: ip addr show

70. netstat: A command for displaying network connections and statistics. Example usage: netstat -tulpn

71. iptables: A command for configuring and managing firewall rules. Example usage: sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT

72. systemctl: A command for managing system services. Example usage: sudo systemctl status sshd

73. journalctl: A command for querying and displaying system logs. Example usage: sudo journalctl -u sshd

74. find: A command for searching for files in a directory hierarchy. Example usage: find /path/to/dir -name *.txt

75. grep: A command for searching for text patterns in files. Example usage: grep 'pattern' /path/to/file

LINUX SCRIPT COMMANDS:

1. echo: A command that displays a message on the terminal. Example usage: echo "Hello World"

2. read: A command that reads a value from the user and stores it in a variable. Example usage: read NAME

3. if: A command that allows you to execute different commands depending on whether a condition is true or false. Example usage: if [ $NAME == "Alice" ] then echo "Hello Alice" else echo "Hello $NAME" fi

4. for: A command that allows you to execute a command for each element in a list. Example usage: for i in 1 2 3 4 5 do echo $i done

5. while: A command that allows you to execute a command repeatedly while a condition is true. Example usage: while [ $i -lt 10 ] do echo $i i=$((i+1)) done

6. case: A command that allows you to execute different commands depending on the value of a variable. Example usage: case $i in

echo "One"
;;

echo "Two"
;;

*) echo "Other" ;; Esac

7. export: A command that allows you to set an environment variable that will be available to child processes. Example usage: export PATH=$PATH:/usr/local/bin

8. source: A command that allows you to execute a script in the current shell, rather than creating a new shell. Example usage: source script.sh

9. alias: A command that allows you to create a shortcut for a longer command. Example usage: alias ll='ls -alF'

10. function: A command that allows you to define a function that can be called like a command. Example usage: function greet { echo "Hello $1" }

greet "Alice"

11. break: A command that allows you to exit out of a loop. Example usage: for i in 1 2 3 4 5 do if [ $i -eq 3 ] then break fi echo $i done

12. continue: A command that allows you to skip an iteration of a loop. Example usage: for i in 1 2 3 4 5 do if [ $i -eq 3 ] then continue fi echo $i done

13. return: A command that allows you to return a value from a function. Example usage: function add { return $(($1 + $2)) }

sum=$(add 2 3) echo $sum

14. basename: A command that allows you to get the base name of a file. Example usage: basename /path/to/file.txt

15. dirname: A command that allows you to get the directory name of a file. Example usage: dirname /path/to/file.txt

16. touch: A command that allows you to create a new empty file or update the modification time of an existing file. Example usage: touch new_file.txt touch existing_file.txt

17. chmod: A command that allows you to change the permissions of a file. Example usage: chmod 755 script.sh

18. chown: A command that allows you to change the owner of a file. Example usage: chown alice:users file.txt

19. ln: A command that allows you to create a link to a file. Example usage: ln -s /path/to/file.txt link.txt

20. sed: A command that allows you to perform text transformations on a file. Example usage: sed 's/foo/bar/g' file.txt

21. awk: A command that allows you to extract and manipulate data from a file. Example usage: awk '{ print $1 }' file.txt

22. grep: A command that allows you to search for a pattern in a file. Example usage: grep 'pattern' file.txt

23. cut: A command that allows you to extract columns of text from a file. Example usage: cut -f 1,3 -d ',' file.csv

24. sort: A command that allows you to sort the lines in a file. Example usage: sort file.txt

25. uniq: A command that allows you to remove duplicates from a file. Example usage: uniq file.txt

26. tee: A command that allows you to write to a file and also output to the terminal. Example usage: echo "Hello World" | tee file.txt

27. head: A command that allows you to display the first few lines of a file. Example usage: head file.txt

28. tail: A command that allows you to display the last few lines of a file. Example usage: tail file.txt

29. cat: A command that allows you to concatenate files and output them to the terminal. Example usage: cat file1.txt file2.txt

30. xargs: A command that allows you to pass the output of one command as arguments to another command. Example usage: find . -name "*.txt" | xargs grep "pattern"

31. tr: A command that allows you to translate characters in a file. Example usage: tr 'a-z' 'A-Z' < file.txt

32. expr: A command that allows you to perform arithmetic operations. Example usage: expr 2 + 3

33. bc: A command that allows you to perform floating point arithmetic operations. Example usage: echo "scale=2; 5/2" | bc

34. date: A command that allows you to display or set the system date and time. Example usage: date

35. cal: A command that allows you to display a calendar for the current month or year. Example usage: cal

36. bc: A command that allows you to perform floating point arithmetic operations. Example usage: echo "scale=2; 5/2" | bc

37. cut: A command that allows you to extract columns of text from a file. Example usage: cut -f 1,3 -d ',' file.csv

38. sort: A command that allows you to sort the lines in a file. Example usage: sort file.txt

39. uniq: A command that allows you to remove duplicates from a file. Example usage: uniq file.txt

40. paste: A command that allows you to merge lines from multiple files. Example usage: paste file1.txt file2.txt

41. dirname: A command that allows you to get the directory name of a file. Example usage: dirname /path/to/file.txt

42. basename: A command that allows you to get the base name of a file. Example usage: basename /path/to/file.txt

43. cut: A command that allows you to extract columns of text from a file. Example usage: cut -f 1,3 -d ',' file.csv

44. wc: A command that allows you to count the number of lines, words, and characters in a file. Example usage: wc file.txt

45. head: A command that allows you to display the first few lines of a file. Example usage: head file.txt

46. tail: A command that allows you to display the last few lines of a file. Example usage: tail file.txt

47. echo: A command that allows you to display a message on the terminal. Example usage: echo "Hello World"

48. sleep: A command that allows you to pause the execution of a script for a specified amount of time. Example usage: sleep 5

49. read: A command that allows you to read input from the user. Example usage: echo "What is your name?" read name echo "Hello, $name!"

50. seq: A command that allows you to generate a sequence of numbers. Example usage: seq 1 10