Essential Linux commands include:

1. **File Operations:**
<div class="terminal-output"><pre><code>$ ls      # List files and directories

$ cd # Change directory
$ pwd # Print working directory
$ cp # Copy files
$ mv # Move/rename files
$ rm # Remove files
$ mkdir # Create directory

2. **System Information:**
<div class="terminal-output"><pre><code>$ top     # Show processes

$ df # Show disk usage
$ free # Show memory usage
$ ps # Show process status

3. **Text Processing:**
<div class="terminal-output"><pre><code>$ grep    # Search text

$ sed # Stream editor
$ awk # Text processing
$ cat # View file contents