Master Real-Time Log Monitoring on Linux: tail, multitail, lnav & less

In Linux, several commands enable real‑time monitoring of log files.

1. tail Command – Monitor Logs in Real Time

The most common way is using tail with the -f option: $ sudo tail -f /var/log/apache2/access.log Alternatively, the tailf command has -f built in, so you can run: $ sudo tailf /var/log/apache2/access.log When logs are rotated, use the -F option to follow a newly created file with the same name: $ sudo tail -F /var/log/apache2/access.log To display only the last two lines while following, combine -n and -f:

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

2. Multitail Command – Monitor Multiple Log Files in Real Time

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

$ sudo apt install multitail   [On Debian & Ubuntu]
$ sudo yum install multitail   [On RedHat & CentOS]
$ sudo dnf install multitail   [On Fedora 22+]

Run it to view two logs simultaneously:

$ sudo multitail /var/log/apache2/access.log /var/log/apache2/error.log

3. lnav Command – Monitor Multiple Log Files in Real Time

Install lnav similarly:

$ sudo apt install lnav   [On Debian & Ubuntu]
$ sudo yum install lnav   [On RedHat & CentOS]
$ sudo dnf install lnav   [On Fedora 22+]

Start lnav with multiple files:

$ sudo lnav /var/log/apache2/access.log /var/log/apache2/error.log

4. less Command – Display Real‑Time Output of Log Files

You can use less and press Shift+F to follow a file, similar to tail -f. The same effect can be achieved by launching less with the +F option: sudo less +F /var/log/apache2/access.log These commands provide flexible ways to watch logs as they grow, handle log rotation, and monitor multiple files at once.

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