Logrotate implements Catalina.out log rotation every two hours

1. Introduction to Logrotate tool

Logrotate is a log file management tool. It is a log cutting tool that comes with Linux by default. Used to rotate, compress, delete old files, and create new log files. We can dump log files according to their size, number of days, etc., to facilitate log file management. This is usually done through cron scheduled tasks, allowing log cutting to be split by hour, by day, etc.

2. Logrotate operation mechanism

The system will run logrotate regularly, usually once a day. This is how the system is implemented on a daily basis. crontab will execute the script in the /etc/cron.daily directory at regular intervals every day, and there is a file called logrotate in this directory.

[root@test01 ~]# cat /etc/cron.daily/logrotate
#!/bin/sh
/usr/sbin/logrotate -s /var/lib/logrotate/logrotate.status /etc/logrotate.conf

EXITVALUE=$?

if [ $EXITVALUE != 0 ]; then

  /usr/bin/logger -t logrotate "ALERT exited abnormally with [$EXITVALUE]"
fi
exit 0

When actually running, Logrotate will call the configuration file /etc/logrotate.conf

3. Composition of Logrotate

/usr/sbin/logrotate #Program location;

/etc/cron.daily/logrotate #By default, Cron executes logrotate once a day;

/etc/logrotate.conf #Global configuration file;

/etc/logrotate.d/ #Use your own configuration file storage directory to override the global configuration;

Note: logrotate.d is a directory. All files in this directory will be automatically read into /etc/logrotate.conf for execution. In addition, if some details are not set in the files in /etc/logrotate.d/, the settings in the file /etc/logrotate.conf will be used as the default values.

4. Logrotate command format

logrotate [OPTION...] <configfile>
-d, --debug: debug mode, test the configuration file for errors.
-f, --force : Force dump file.
-m, --mail=command: After compressing the logs, send them to the specified mailbox.
-s, --state=statefile : Use the specified state file.
-v, --verbose : Display the dump process.

For example: you want to force the rotation of log files without waiting for logrotate to do so.

[root@test01 ~]# /usr/sbin/logrotate -vf /etc/logrotate.d/tomcat #I use it for testing. Note: CentOS7 commands are in /usr/sbin/.

5. Description of common configuration parameters

The most important thing for the implementation of Logrotate function is its configuration parameters

The following are its commonly used configuration parameters:

6. Install and configure Logrotate

#yum installation

[root@test01 ~]# yum -y install logrotate

#The machine has already installed Tomcat. Now configure the configuration file for cutting Tomcat logs.

[root@test01 ~]# vim /etc/logrotate.d/tomcat

Note: The configuration file for logrotate is /etc/logrotate.conf and usually does not need to be modified.

The log file rotation settings are in separate configuration files, which are placed in the /etc/logrotate.d/ directory.

[root@test01 ~]# mkdir -p /var/log/tomcat/oldlog

[root@test01 ~]# cat /etc/logrotate.d/tomcat

/usr/local/tomcat8/logs/catalina.out { #Log paths to be cut, if there are multiple, separate them with spaces notifempty #If the log is empty, it will not be rotated (that is, empty logs will not be cut)

  rotate 5000 #Retain the previous data for a maximum of 5000 times during rotation missingok #If a log is lost, continue to roll the next log without reporting an error compress #Enable compression, which refers to the old log after rotation. The default compression here is gzip dateext #Use the current date as the naming format dateformat .%Y%m%d-%H dot #Use with dateext, appear immediately on the next line, define the file name after the file is cut, must be used with dateext, only supports %Y %m %d %s

  olddir /var/log/tomcat/oldlog #The log files after rotation are placed in the specified directory}

Note: I did not set how often to cut in this configuration, but it is cut once a day, because when the /etc/logrotate.d/tomcat file is not configured, the default is to execute the /etc/cron.daily/logrotate file every day, and this file is cut once a day.

#Force the execution of cutting and check whether there is a log in /var/log/tomcat/oldlog

[root@test01 ~]# /usr/sbin/logrotate -vf /etc/logrotate.d/tomcat

reading config file /etc/logrotate.d/tomcat

olddir is now /var/log/tomcat/oldlog

Allocating hash table for state file, size 15360 B

Handling 1 logs

rotating pattern: /usr/local/tomcat8/logs/catalina.out forced from command line (5000 rotations)

olddir is /var/log/tomcat/oldlog, empty log files are not rotated, old logs are removed

considering log /usr/local/tomcat8/logs/catalina.out

 log needs rotating

rotating log /usr/local/tomcat8/logs/catalina.out, log->rotateCount is 5000

Converted '.%Y%m%d-%H点' -> '.%Y%m%d-%H点'

dateext suffix '.20181226-15'

glob pattern '.[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]-[0-9][0-9]dot'

glob finding old rotated logs failed

fscreate context set to unconfined_u:object_r:usr_t:s0

renaming /usr/local/tomcat8/logs/catalina.out to /var/log/tomcat/oldlog/catalina.out.20181226-15:00 compressing log with: /bin/gzip

set default create context to unconfined_u:object_r:usr_t:s0

set default create context

# View cutting results

#Delete the previously cut file, because the file will be the same when cut again, which is catalina.out.20181226-15.gz file, so the cutting will not be successful.

[root@test01 ~]# rm -rf /var/log/tomcat/oldlog/catalina.out.20181226-15点.gz 
[root@test01 ~]# ls /var/log/tomcat/oldlog/
[root@test01 ~]#

#Set a scheduled task to cut once every minute (Note: the log must have content, because the empty log file defined earlier is not cut)

[root@test01 ~]# crontab –e
*/1 * * * * /usr/sbin/logrotate -vf /etc/logrotate.d/tomcat >>/var/log/tomcat/oldlog/cutting.log

# Cut every two hours

[root@test02 ~]# crontab -l
0 */2 * * * /usr/sbin/logrotate -vf /etc/logrotate.d/tomcat >> /root/chenjiaxin/cutting.log

#View the results of timed cutting

Of course, the above setting of cutting once a minute is so that the experiment can see the effect as soon as possible. In fact, it is necessary to set how often to cut logs according to the needs of the company!

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