Master Real-Time Log Monitoring on Linux with Tail, Multitail, Lnav & Less

Real‑time Log Viewing on Linux

Linux provides several utilities to display log file contents as they grow, with tail being the most common.

1. tail Command – Monitor Logs in Real Time

The basic

-f

option follows a file:

<code>$ sudo tail -f /var/log/apache2/access.log</code>

Alternatively, the

tailf

command has

-f

built‑in, so you can simply run:

<code>$ sudo tailf /var/log/apache2/access.log</code>

For rotating logs, use

-F

to follow a file by name even after it is recreated:

<code>$ sudo tail -F /var/log/apache2/access.log</code>

If you only need the last two lines in real‑time, combine

-n

and

-f

:

<code>$ sudo tail -n2 -f /var/log/apache2/access.log</code>

2. Multitail Command – Monitor Multiple Log Files

Install Multitail on Debian/Ubuntu, RedHat/CentOS, or Fedora:

<code>$ sudo apt install multitail   [On Debian &amp; Ubuntu]</code>
<code>$ sudo yum install multitail   [On RedHat &amp; CentOS]</code>
<code>$ sudo dnf install multitail   [On Fedora 22+]</code>

Display two logs side by side:

<code>$ sudo multitail /var/log/apache2/access.log /var/log/apache2/error.log</code>

3. lnav Command – Monitor Multiple Log Files

Install Lnav similarly:

<code>$ sudo apt install lnav   [On Debian &amp; Ubuntu]</code>
<code>$ sudo yum install lnav   [On RedHat &amp; CentOS]</code>
<code>$ sudo dnf install lnav   [On Fedora 22+]</code>

View two logs together:

<code>$ sudo lnav /var/log/apache2/access.log /var/log/apache2/error.log</code>

4. less Command – Real‑time Output with Shift+F

Open a log with

less

and press

Shift+F

(or start with

+F

) to follow the file:

<code>sudo less +F /var/log/apache2/access.log</code>

Further Reading

Manage Files Effectively using head, tail and cat Commands in Linux

How to Setup and Manage Log Rotation Using Logrotate in Linux

Petiti – An Open Source Log Analysis Tool for Linux SysAdmins

How to Query Audit Logs Using ‘ausearch’ Tool on CentOS/RHEL

Manage Log Messages Under Systemd Using Journalctl (Comprehensive Guide)