tailf Command in Linux

DESCRIPTION

tailf will print out the last 10 lines of a file and then wait for the file to grow. It is similar to tail -f but does not access the file when it is not growing. This has the side effect of not updating the access time for the file, so a filesystem flush does not occur periodically when no log activity is happening. tailf is extremely useful for monitoring log files on a laptop when logging is infrequent and the user desires that the hard disk spin down to conserve battery life.

SYNOPSIS

tailf [OPTION] file

OPTION :

-n, –lines=N, -N
output the last N lines, instead of the last 10.

EXAMPLES

1. Display the last 5 lines and then update the file as new lines are being added

$ tailf -n 5 myfile.txt

This is a great command to use to watch log files or logs in real-time.

2. If you’re trying to view a file such as the Apache access log file that is updated frequently you can pipe its output through the grep command to filter out only the content you want.

$ tailf access.log | grep 24.10.160.10

In this above example, we’re watching the access.log for any IP address of 24.10.160.10