tail -f for live log monitoring in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the command tail -f filename do?

It shows the last lines of the file named filename and keeps the terminal open to display new lines added to the file in real-time.

beginner

Why is tail -f useful for monitoring logs?

Because it lets you watch new log entries as they happen, like watching a live news feed, so you can quickly see updates or errors.

beginner

How can you stop the tail -f command once it is running?

You can stop it by pressing Ctrl + C on your keyboard, which interrupts the command and returns you to the prompt.

beginner

What is the difference between tail filename and tail -f filename?

tail filename shows the last few lines once and exits. tail -f filename shows the last lines and then keeps running to show new lines as they are added.

intermediate

Can tail -f be used on any file?

Yes, but it is most useful on files that are actively updated, like log files. For static files, it will just show the last lines and wait without new updates.

What does the -f option do in the tail command?

A Shows the first lines of the file

B Keeps showing new lines added to the file in real-time

C Deletes the file after reading

D Copies the file to another location

The -f option makes tail follow the file, showing new lines as they are added.

How do you stop a running tail -f command?

A Press Ctrl + C

B Press Ctrl + Z

C Close the terminal window

D Type exit

Pressing Ctrl + C sends an interrupt signal to stop the command.

Which file type is tail -f most useful for?

A Binary executable files

B Static text files that never change

C Log files that update frequently

D Image files

Log files update often, so tail -f helps watch new entries live.

What will tail -f /var/log/syslog show?

A The last lines of the syslog file and new lines as they appear

B The first lines of the syslog file

C The entire syslog file at once

D Nothing, it will give an error

This command shows the end of the syslog and updates live as new logs are added.

If you want to see only the last 20 lines of a file once, which command do you use?

A cat filename

B tail -f filename

C head -n 20 filename

D tail -n 20 filename

tail -n 20 filename shows the last 20 lines once and exits.

Explain how the tail -f command helps in live log monitoring.

Think about watching a live event or news feed.

Describe how to start and stop live monitoring of a log file using tail.

Starting is with a command, stopping is with a keyboard shortcut.