9. tail

The tail command is a fundamental utility for anyone learning Linux. As its name suggests, it allows you to view the "tail" or end of a file. This is particularly useful for checking the most recent entries in rapidly changing files, such as system logs.

Viewing the End of a File

By default, the tail command displays the last 10 lines of a specified file. It functions as the counterpart to the head command.

tail /var/log/syslog

Just like with head, you can customize the number of lines you want to see by using the -n option. For example, to see the last 20 lines, you would use the following command:

tail -n 20 /var/log/syslog

This flexibility makes the Linux tail command an essential tool for quickly inspecting file endings without opening the entire file.

Real-Time File Monitoring with tail -f

One of the most powerful features of the tail command is its ability to monitor files in real-time. This is achieved with the -f (follow) flag. When you use tail -f, the command doesn't exit after displaying the last few lines. Instead, it waits for new data to be appended to the file and prints it to the screen as it arrives.

tail -f /var/log/syslog

Try running this command. As you continue to use your system, you will see new lines appear in your terminal. This makes tail -f an indispensable tool for system administrators and developers who need to view logs and monitor application output as it happens.