How To Limit The Growth Of UNIX / Linux Log Files

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Q. My log files grow continuously. How do I limit the growth of UNIX log files stored in /usr/spool/ or /var/log/ directory?

A. The log files could be the only source of information available to trace a problem or security issues. Log files keep growing every day as new logging data are appended onto existing log files. If you failed to manage log files, it will eat out disk space and no space will be left on filesystem to store user data. To avoid such problems try following solutions:

Keep log files in a separate filesystem

Never ever store /var/log or /var/adm and all other location on a / (root) filesysem. Always store all log files on a separate filesystem to maintain the security, integrity and performance of the system.

Control the growth of system log files

There are varios approaches to control the growth of system log files.

Option # 1: Manually truncate log file

Use any one of the following command to truncate log file:
# >/var/log/log.file
# cat /dev/null > /usr/adm/log.file

Option # 2: Automatically truncate log file

You need to keep several old versions of a log file in the system by periodically deleting the oldest one, renaming the current one, and then recreating it. This can be done by using a shell script or using automated tool such as logrotate.

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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  1. you can use logrotate – /usr/sbin/logrotate
    you can for example start a new, empty log every day. and the old log is renamed to log.1 log.2 log.3 and so on.

    so you keep all the logs in tiny pieces and can delete parts of the logs, instead always the whole log.

  2. Logrotate also let you delete some of the log which are for example older than 90, 180 and so on days.
    You can have different setting for each log file you want to maintenance.

    Very useful tool.

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