# Logrotate Notes

This is a quick overview of logrotate which… umm… rotates log files. This was written for CentOS/RHEL 5.5.

## Pertinent Files & Directories

File/Dir Purpose
/usr/sbin/logrotate The command itself.
/etc/cron.daily/logrotate Bash script that executes the logrotate command every day.
/etc/logrotate.conf and /etc/logrotate.d/ Rotation defaults if they are not defined for specific daemons. You can add rotate configs to this file, or put them in /etc/logrotate.d
/var/lib/logrotate.status Show when the specified log files were last rotated.

## Logrotate Options

Quite simple, really. The man page elucidates all available options. Here’s a quick table of what the most commonly used ones do.

Option Purpose
rotate <number> Keep specified number of logfiles before they are deleted and/or emailed to admin
size=<number> Rotate logs when they reach this size.
This is done ‘‘without regard’’ for the last rotated time.
Use minsize <number> if you’d like to balance both time and size.
Bytes are used without a specifier. 100k, 100M are also fine.
daily Rotate daily. This is the default minimum granularity, unless you move /etc/cron.daily/logrotate to /etc/cron.hourly/logrotate
weekly Rotate weekly
monthly Rotate monthly
notifempty Don’t rotate if empty (the reverse, ifempty, is default)
missingok If log file is missing for some reason, move on without error
compress Compress logfile after rotation.
Default is gzip with -9 (maximum) compression.
The choice of compression program can be changed with compresscmd (e.g. compresscmd bzip2).
To pass options (like compression level), use compressoptions.
To change extension of compressed file, use compressext
dateext Use YYYYMMDD format instead of just tacking on numbers (like .0, .1 and so on) to the rotated files.
mail <recipient> Email recipient the file that will be deleted after a rotation cycle
create <mode> <owner> <group> Create logfiles with the specified permissions and owner:group attributes.
olddir <directory> Move all but the newest log file to this directory (nice to keep things organized)

### Other (kinda important) options

You’ll see these used with Apache, for instance.

Option Purpose
prerotate Execute the a script ‘‘before’’ rotating a log. Should end this with endscript.
postrotate Execute the a script ‘‘after’’ rotating a log. Should end this with endscript.
sharedscripts Make sure that the script(s) specified in prerotate and/or postrotate run just ‘‘once’’ (i.e. not for ‘’every’’ logfile)
delaycompress Don’t compress yesterday’s logfile (if daily… you get the picture)

## Example

Here’s a real-world application of the above. I want to rotate an already huge log of OpenVPN connections (~32M in size) like so:

• I want to maintain 60 days worth of logs
• Logfile size doesn’t matter to me
• The files should be rotated in YYYYMMDD format
• They should be compressed (the default gzip -9 is fine)
• They should be organized; older logfiles should be in a separate directory

The logfile is at /var/log/openvpn/connections.log. Here’s the configuration file I created for the above. It’s /etc/logrotate.d/openvpn:

/var/log/openvpn/connections.log {
daily
rotate 60
dateext
compress
olddir /var/log/openvpn/old

nomail
missingok
notifempty
delaycompress
create 640 root root
}


To test this, I run:

logrotate -d /etc/logrotate.d/openvpn


The -d switch runs it in verbose, debug, dry-run mode (i.e. nothing actually happens.)

## Other Stuff

### Leopard and Snow Leopard

These use a new utility called newsyslog. It is invoked every minute by:

/System/Library/LaunchDaemons/com.apple.newsyslog.plist


The config file for this is /etc/newsyslog.conf and is kinda nicer than logrotate’s config :)