Get to know the command line: Linux CLI basics

Mastering Server Management through SSH

Introduction

Get to know the command line: Linux CLI basics. Navigating your Pressillion server via SSH might seem daunting initially, especially if you’re not a developer.

However, SSH access is an invaluable tool, granting direct server management capabilities.

This guide aims to demystify SSH and equip you with essential commands for efficient server management on Pressillion.

Part 1. A Quick Introduction to SSH

SSH (Secure Shell) enables secure connections between computers. On Pressillion, SSH is the primary method for server access, ensuring encrypted, secure interactions between your local machine and servers.

SSH and WordPress

While FTP/SFTP provides file access, SSH allows file viewing/editing, zipping/unzipping, database backups, and more—offering fast, secure, and efficient server management. It’s favored by sysadmins for WordPress site management.

Connecting to your server by SSH

Guides are available for creating SSH keys and adding them to servers.

Follow these steps:

  1. Generate your SSH Key
  2. Add your SSH Key to Pressillion
  3. Connect to your server using SSH

Part 2. Navigation – Commands you’ll use a lot

Mastering key commands for server navigation is fundamental for effective management:

ls – The list command

Use ls to list directory contents:

  • ls -l – Display detailed information including permissions.
  • ls -a – Show all files including hidden ones.
  • ls -lh – List with file sizes in human-readable form.
cd – Change Directory

Navigate directories with cd:

  • cd ~ – Go to the root directory.
  • cd .. – Move to the directory above the current one.
  • cd - – Return to the previous directory.
Arrow keys, Home & End

Use arrow keys for quick command history access and Home/End for navigation.

Part 3. Active Server Management Commands

Learn commands for making changes to your server actively:

Create a directory

Use mkdir to create a directory:

  • mkdir mynewdirectory – Create a new folder in a specific location.
Creating new files

Utilize touch to create files:

  • touch newphpfile.php – Generate a new PHP file.
Copy

Duplicate files/folders with cp:

  • cp main-context.conf /_custom/main-context.conf – Copy a file to a new location.
  • cp -f, cp -i, cp -n – Variations for different copy scenarios.
Move

Transfer files/directories with mv:

  • mv SOURCE DESTINATION – Move files to a specified destination.
  • Various options for moving and renaming files.
Viewing the contents of existing Files

View file contents using cat, head, tail:

  • cat wp-config.php – Display entire file contents.
  • head, tail, tail -f – Show parts of a file or view in real-time.
Remove (delete) stuff

Delete files/folders using rm:

  • rm myoldfile.txt – Remove a specific file.
  • rm -r directoryname – Delete an entire directory and its contents.
View File sizes

Check disk usage with du:

  • du -h, du -sh – Display disk usage in a human-readable format.
View System Disk Space

Check system disk space using df:

  • df -h, df -T – View disk space usage in a human-readable format and system file types.

Part 4. Creating and editing files

Create/edit files using nano:

  • nano newphpfile.php – Open a PHP file for editing.
  • Use CTRL+O, CTRL+X to save and exit in nano.

Part 5. Working with Compressed Files

Manage compressed files, zipping, and unzipping operations:

Zip

Use zip to compress directories:

  • zip /var/www/example.com/htdocs – Zip a directory.
  • zip -m filename.zip foldername – Compress and delete the original.
  • zip -d filename.zip foldername – Delete a file from an existing zip archive.
Unzip

Unzip files using unzip:

  • unzip filename.zip – Unzip a file.
  • unzip filename.zip -x excludeme.ext – Exclude specific files/directories.
  • unzip filename1.zip filename2.zip filename3.zip – Unzip multiple files simultaneously.
List the contents of a Zip File

View contents of a zipped file with unzip -l:

  • unzip -l filename.zip – Display contents of a zipped file.
Creating Tar Files

Create tar files for archiving:

  • tar -cf tarfilename.tar /target/directory – Create a .tar file.
  • tar -cvf tarfilename.tar /target/directory – Create a .tar file with verbose output.
  • tar -cvzf tarfilename.tar /target/directory – Compress while creating a .tar file.
Extracting Tar Files

Extract tar files:

  • tar -xf tarfilename.tar – Extract a .tar file.
  • tar -xvf tarfilename.tar – Extract a .tar file with verbose output.

Part 6. Searching your system

Discover files/data within your server:

find – Find files and directories

Locate files using find:

  • find starting/path criterion "search term" – Search for specific files/directories.
  • Examples using find command for searching directories and files.
grep – Search files by content

Use grep to find content inside files:

  • grep searchword/term filename – Search for a word/term in a file.
  • Various options like -i, -c, -n, -l for different search scenarios.

Part 7. Monitoring your system

Monitor server activity using built-in tools like top and htop.

Part 8. Other useful commands

Additional commands for various server tasks:

wget – Download from a website

Download files from external sources with wget:

  • wget OPTIONS URL – Options for downloading files.
pwd – Print name of current/working directory

Display the current directory path with pwd.

Clear your terminal window

Clear the terminal window for a neat interface:

  • Use clear command or press CTRL+L.

Part 9. The Linux Manual

Access the Linux manual (man command) for in-depth information on commands:

  • man whatis – Display a one-line manual page description.
  • Lookup commands directly in the Linux manual for comprehensive details.

Part 10. Exit

To disconnect from servers:

  • Use exit.