The 'tail' command is a powerful and essential utility for any systems engineer or developer working in a Unix-based environment, including macOS. It allows you to display the last part of files, which is particularly useful for monitoring log files, debugging, and verifying the end of lengthy outputs. This article will guide you through the usage of the 'tail' command on macOS, highlighting its importance and providing practical examples.

Examples:

1. Basic Usage of 'tail': To display the last 10 lines of a file, you can use the following command:

   tail /path/to/your/file.txt

   Example:

   tail /var/log/system.log

   This command will show the last 10 lines of the system log file.

2. Displaying a Specific Number of Lines: You can specify the number of lines to display using the -n option:

   tail -n 20 /path/to/your/file.txt

   Example:

   tail -n 20 /var/log/system.log

   This command will display the last 20 lines of the system log file.

3. Monitoring a File in Real-Time: The -f option allows you to follow a file in real-time, which is useful for monitoring log files as they are being written:

   tail -f /path/to/your/file.txt

   Example:

   tail -f /var/log/system.log

   This command will continuously display new lines added to the system log file.

4. Combining Options: You can combine options to tailor the output to your needs. For instance, to follow a file and display the last 50 lines:

   tail -n 50 -f /path/to/your/file.txt

   Example:

   tail -n 50 -f /var/log/system.log

   This command will show the last 50 lines of the system log file and continue to display new lines as they are added.

5. Using 'tail' with Pipes: You can use tail in combination with other commands using pipes. For example, to filter the output of tail:

   tail -f /path/to/your/file.txt | grep "ERROR"

   Example:

   tail -f /var/log/system.log | grep "ERROR"

   This command will display lines containing "ERROR" from the system log file in real-time.