Operations grimoire/Logs

Logs are generally located in /var/log directory, but can also be in specialized systems (e.g. Docker)

How to create a logrotate configuration (Linux) Logrotate is a utility in Linux that manages log file rotation, archiving, and deletion automatically to prevent logs from consuming all disk space. The configuration is usually placed in /etc/logrotate.conf for global settings and in /etc/logrotate.d/ for application-specific log policies.​

To configure logrotate for a specific service, create a file in /etc/logrotate.d/, for example /etc/logrotate.d/nginx, and add a block describing how the log files should be rotated:

/var/log/nginx/*.log {

   daily
   rotate 7
   compress
   missingok
   notifempty
   create 640 root adm
   postrotate
       systemctl reload nginx > /dev/null
   endscript

}

How the rotation works: When logrotate runs (automatically via cron or manually), it checks each log file per the configuration, archives old logs, creates new ones, and triggers the specified post-rotation actions.

For reference, see the full documentation:

https://wiki.archlinux.org/title/Logrotate

Log rotation

Newsyslog

To create a configuration for newsyslog under FreeBSD, you need to add or modify a line in the main file /etc/newsyslog.confor in an auxiliary configuration file, often specific to a service.​

/var/log/www/*/*.log root:web 640 90 * @T00 JC /var/run/nginx.pid 30

If you're manipulating patterns with wildcards (like *), don't forget the option G. Otherwise, the system might create a literal file named ` *` or not process the files as expected.

For a field-by-field explanation, see the man page:

https://man.freebsd.org/cgi/man.cgi?newsyslog.conf(5)