Monitoring and logging are essential components of system administration and automation. They help you keep track of system performance, detect issues early, and maintain a record of system activities. In this section, we will cover the basics of monitoring and logging in Bash, including practical examples and exercises.

1. Monitoring: The process of continuously observing system performance and resource usage.
2. Logging: The practice of recording system events and activities for future reference and analysis.
3. Tools: Common tools used for monitoring and logging in Bash include top, htop, vmstat, iostat, dmesg, and log files.

• top: A command-line utility that provides a dynamic, real-time view of system processes.
• htop: An interactive process viewer for Unix systems, similar to top but with a more user-friendly interface.

Example: Using top

Explanation:

• Running the top command will display a real-time list of running processes, including their CPU and memory usage.

Example: Using htop

Explanation:

• htop provides a more interactive and visually appealing interface compared to top. You can navigate through processes using arrow keys and perform actions like killing processes.

• vmstat: Reports information about processes, memory, paging, block IO, traps, and CPU activity.
• iostat: Reports CPU and input/output statistics for devices and partitions.

Example: Using vmstat

Explanation:

• The vmstat command with an interval of 5 seconds will display system performance statistics every 5 seconds.

Example: Using iostat

Explanation:

• The iostat command with an interval of 5 seconds will display CPU and I/O statistics every 5 seconds.

• dmesg: Displays the kernel ring buffer messages, which can be useful for diagnosing hardware and driver issues.

Example: Using dmesg

Explanation:

• The dmesg command with tail -20 will display the last 20 lines of the kernel ring buffer messages.

• System log files are typically stored in the /var/log directory.
• Common log files include /var/log/syslog, /var/log/auth.log, and /var/log/kern.log.

Example: Viewing Log Files

Explanation:

• The tail -f command will display the last few lines of the /var/log/syslog file and continuously update it as new log entries are added.

1. Use the top or htop command to monitor CPU and memory usage on your system.
2. Identify the process consuming the most resources.

Explanation:

• Run either top or htop and observe the processes. Look for the process with the highest CPU or memory usage.

1. Use the iostat command to check disk I/O statistics.
2. Identify any disks with high I/O activity.

Explanation:

• Run the iostat command with an interval of 5 seconds and observe the I/O statistics for each disk.

1. Use the dmesg command to view recent kernel messages.
2. Use the tail command to view the last 20 lines of the /var/log/syslog file.

Explanation:

• The dmesg | tail -20 command will display the last 20 lines of kernel messages.
• The tail -20 /var/log/syslog command will display the last 20 lines of the system log file.

• Mistake: Ignoring log files.
  • Tip: Regularly check log files for any unusual activity or errors.
• Mistake: Not using monitoring tools effectively.
  • Tip: Familiarize yourself with different monitoring tools and use them to keep track of system performance.

In this section, we covered the basics of monitoring and logging in Bash. We explored various tools like top, htop, vmstat, iostat, and dmesg, and learned how to work with log files. By mastering these tools, you can effectively monitor system performance and maintain comprehensive logs for troubleshooting and analysis. In the next module, we will delve into best practices and optimization techniques for Bash scripting.