Linux Fundamentals — Essential Commands

#linux #bash #commands #sysadmin

File System Navigation

pwd          # Print working directory
ls -la       # List all files with details
cd /path     # Change directory
find / -name "file.txt"  # Search for files

File Permissions

Linux uses a permission model: Owner / Group / Others with Read (4) / Write (2) / Execute (1).

chmod 755 script.sh    # rwxr-xr-x
chown user:group file  # Change ownership

Process Management

ps aux       # List all processes
top          # Real-time process monitor
kill -9 PID  # Force kill a process

Networking Commands

ifconfig / ip a    # Show network interfaces
netstat -tulpn     # Active connections
ss -tulpn          # Modern alternative
curl / wget        # Download files

Essential for Pentesting

• grep — Search file contents
• awk / sed — Text processing
• crontab -l — Scheduled tasks (priv esc vector)
• /etc/passwd and /etc/shadow — User credential files