Monitoring system resources is a critical task for ensuring the smooth operation of Linux systems. This article will guide you through various command-line tools available in Linux to monitor CPU, memory, disk usage, and network activity.

Examples:

1. Monitoring CPU Usage with top and htop:

   The top command provides a real-time view of the system's CPU usage, memory usage, and running processes.

   top

   For a more user-friendly interface, you can use htop, which is not installed by default on all systems but can be installed via package managers like apt or yum.

   sudo apt-get install htop   # For Debian-based systems
   sudo yum install htop       # For Red Hat-based systems
   htop

2. Checking Memory Usage with free:

   The free command displays the total amount of free and used physical and swap memory in the system.

   free -h

   The -h option provides the output in a human-readable format.

3. Monitoring Disk Usage with df and du:

   To check disk space usage, use the df command:

   df -h

   The -h option makes the output human-readable. To see disk usage for specific directories, use the du command:

   du -sh /path/to/directory

4. Network Activity with iftop and nload:

   iftop is a tool that displays bandwidth usage on an interface by host. It is not installed by default but can be installed using:

   sudo apt-get install iftop   # For Debian-based systems
   sudo yum install iftop       # For Red Hat-based systems
   sudo iftop -i eth0           # Replace eth0 with your network interface

   For a simple view of network traffic, nload can be used:

   sudo apt-get install nload   # For Debian-based systems
   sudo yum install nload       # For Red Hat-based systems
   nload

5. Process Monitoring with ps and kill:

   To view all running processes, use the ps command:

   ps aux

   To terminate a process, use the kill command followed by the process ID (PID):

   kill -9 <PID>

6. System Logs with tail and journalctl:

   To view the last few lines of a log file, use tail:

   tail -f /var/log/syslog

   For systems using systemd, journalctl can be used to view logs:

   journalctl -xe

By using these tools, you can effectively monitor and manage system resources in a Linux environment, ensuring optimal performance and stability.