Linux Network & System Commands

Overview

This lecture covers essential Linux network and system management commands, focusing on configuration, troubleshooting, file operations, resource monitoring, disk usage, and text editing.

Network Configuration & Troubleshooting

• Use the ip command to enable, disable, or configure network interfaces.
• ip address displays current IP configurations for all interfaces.
• The loopback interface uses IP 127.0.0.1, while physical adapters display their own IPs, subnet masks, and MAC info.
• Use ip route to view routing tables.
• The ping command tests connectivity to specific IPs, continuously sending packets until interrupted (Ctrl+C).
• Ping output includes sequence number, time to live (TTL), and roundtrip time.
• Use curl to fetch raw HTML or data from web servers at the command line.
• The dig command queries DNS servers for information, returning IP addresses for domain names.
• traceroute (Linux/Mac: traceroute, Windows: tracert) shows the network path and routers (hops) between your device and a destination.

Working with Files & Documentation

• Use the man command to access built-in Linux documentation for any command.
• The cat command displays file contents or concatenates multiple files into one using redirection (>).

System & Resource Monitoring

• top provides a real-time view of processes, resource usage, and system load over 1, 5, and 15 minutes.
• The ps command lists running processes; ps -e shows all processes, and you can combine it with grep to filter for specific ones.
• Use more to page through long command outputs.

Disk Space Management

• df shows disk space usage for all file systems; use df -h for human-readable output (e.g., GB, MB).
• du -h recursively displays disk usage per directory to help locate large files or folders consuming space.

Editing Files

• Use text editors like nano for modifying configuration or log files within the terminal.
• nano enables navigation, editing, and saving changes using keyboard shortcuts.

Key Terms & Definitions

• IP Command — Tool for managing network interfaces and configurations.
• Loopback Address — Special IP address (127.0.0.1) used for internal network testing.
• Ping — Network tool checking connectivity to a remote device via ICMP packets.
• curl — Command-line tool for transferring data to/from servers.
• dig — DNS lookup utility for querying domain information.
• traceroute — Maps network path and hops to a destination.
• man — Linux manual page viewer.
• cat — Displays or concatenates file content.
• top — Real-time system resource and process monitor.
• ps — Lists running processes.
• df — Shows disk free space.
• du — Shows disk usage by folder/file.
• nano — Full-screen, terminal-based text editor.

Action Items / Next Steps

• Practice using commands: ip, ping, curl, dig, traceroute, man, cat, top, ps, df, du, and nano.
• Explore man pages for these utilities to learn additional options and usage details.