head, as their names suggest, respectively print the beginning and ending of files.
You can easily understand the usages of
tail with this example:
tail -n 50 /var/log/auth.log. This command shows last 50 lines of the
auth.log file. And the usages of
head are alike. There is only one basic and intuitive option.
You wanna lines? Use
-n, and there are
-c for characters,
-b for bytes.
With this knowledge, you can print first 5 characters of a file with command:
head -c 5 filename.
To show a real-time output of a changing file, we can use the
tail -f /var/log/auth.log prints the end of the file and updates the output when lines are appended to file.
It’s really helpful and handy when you debug your Linux system under some circumstances.