Day - 2 Linux Commands for DevOps Engineer

As a DevOps professional, you'll frequently work with Linux systems and utilize various commands to manage and automate tasks. Here are some commonly used Linux commands along with explanations and examples:

1. ls: This command lists files and directories in the current directory.

   Example:

   • ls -l lists files and directories in long format with detailed information.

   • ls -l--> list the files and directories in long list format with extra information

   • ls -a --> list all including hidden files and directory

   • ls *.sh --> list all the files having .sh extension.

   • ls -i --> list the files and directories with index numbers inodes

   • ls -d */ --> list only directories.(we can also specify a pattern)

2. cd: Used to change the current directory.

   Example:

   • cd /var/www changes the current directory to "/var/www".

   • pwd --> print work directory. Gives the present working directory.

   • cd path_to_directory --> change directory to the provided path

   • cd ~ or just cd --> change directory to the home directory

   • cd - --> Go to the last working directory.

   • cd .. --> change directory to one step back.

   • cd ../.. --> Change directory to 2 levels back.

3. pwd: Prints the current working directory.

   • Example: pwd displays the current directory path.

4. mkdir: Creates a new directory.

   Example:

   • mkdir project creates a directory named "project".

   • mkdir directoryName --> to make a directory in a specific location

   • mkdir directoryName # make a new folder 'newFolder'

   • mkdir NewFolder # make a hidden directory (also . before a file to make it hidden)

   • mkdir A B C D #make multiple directories at the same time

   • mkdir /home/user/Mydirectory # make a new folder in a specific location

   • mkdir -p A/B/C/D # make a nested directory

5. rm: Removes files and directories.

   • Example: rm file.txt deletes a file named "file.txt".

   • Example: rm -r directory deletes a directory and its contents recursively.

6. cp: Copies files and directories.

   • Example: cp file.txt /tmp copies "file.txt" to the "/tmp" directory.

7. mv: Moves or renames files and directories.

   • Example: mv file.txt newfile.txt renames "file.txt" to "newfile.txt".

   • Example: mv file.txt /tmp moves "file.txt" to the "/tmp" directory.

8. touch: Creates an empty file or updates the access and modification timestamps of an existing file.

   • Example: touch file.txt creates an empty file named "file.txt".

9. cat: Displays the contents of a file.

   • Example: cat file.txt outputs the content of "file.txt" to the console.

10. grep: Searches for a specified pattern in files.

    • Example: grep "error" logfile.txt searches for the word "error" in "logfile.txt".

11. chmod: Modifies file permissions.

    • Example: chmod +x script.sh grants execute permission to "script.sh".

12. chown: Changes the owner of a file or directory.

    • Example: chown user:group file.txt changes the owner and group of "file.txt".

13. ssh: Connects to a remote machine using the Secure Shell protocol.

    • Example: ssh user@hostname establishes an SSH connection to "hostname" as "user".

14. scp: Securely copies files between local and remote systems using SSH.

    • Example: scp file.txt user@hostname:/path copies "file.txt" to the remote machine at "/path".

15. wget: Downloads files from the web.

    • Example: wget https://example.com/file.zip downloads "file.zip" from the given URL.

These commands are just a starting point, and there are many more available in Linux. Their usage may vary depending on your specific requirements and the tasks you need to accomplish as a DevOps professional.

Hope this is useful for you :)