tailf

Output the last part of a file and follow growth, typically used for log tracking

Description

The tailf command is nearly identical to tail -f, but is more similar to tail --follow=name. It can continue tracking even if the file is renamed, making it ideal for monitoring the growth of log files. Unlike tail -f, it does not access the disk if the file is not growing. tailf is particularly suitable for laptops as it reduces disk access and saves power. Note that tailf is a compiled C binary, not a script, and may not be installed on all Linux distributions.

Differences between tailf and tail -f

1. tailf reads the file incrementally from the beginning, whereas tail -f reads from the end.
2. tailf checks for file growth using the filename and the stat system call; tail -f uses the opened file descriptor. (Note: tail can also track by filename, but it uses fstat rather than stat. Consequently, by default, tail may not realize if a file is deleted, while tailf will).

Syntax

tailf logfile # Dynamically track the log file, initially printing the last 10 lines.

Options

-n, --lines NUMBER  # Output the last N lines.
-NUMBER             # Same as `-n NUMBER`.
-V, --version       # Output version information and exit.
-h, --help          # Display help and exit.

Parameters

Target: Specify the target log file.

Examples

tailf log/WEB.LOG 
tailf -n 5 log2014.log   # Display the last 5 lines of the file