介绍
默认apache日志默认不分割的，长时间不清理apache日志就会占满磁盘空间，而且一个整文件既不利于管理也不利于分析统计。（其他日志也如此）
什么cronolog?
cronolog是一个简单的过滤程序，它从标准输入设备读入日志记录，并把这些记录写入到输出文件集，输出文件的名字由一个文件名模板和当前的日期时间组成。cronolog通常与web服务器一起使用，例如apache,用来安全地对日志文件按日期、月或其它特定的区间进行分割。当然也可以配置来分割其他服务的日志，如nginx,lighttpd。
详情参考 man cronolog，这里用apache举例。
安装cronolog
yum -y install cronolog
cronolog官网已经不用了，但是centos的yum已经包含了该软件，所以可以直接下载
配置
apache的虚拟主机的日志的cronolog配置
cat /app/server/httpd/conf/vhosts/test.com.conf
DocumentRoot /app/www/test.com
ServerName test.com
Options -Indexes FollowSymLinks
DirectoryIndex index.php index.html
AllowOverride all
Order allow,deny
Allow from all
ErrorLog "|/usr/sbin/cronolog /app/server/httpd/logs/test.com-error_%Y%m%d.log"
CustomLog "|/usr/sbin/cronolog /app/server/httpd/logs/test.com_%Y%m%d.log" combined
在虚拟主机基础配置上修改errorlog和customlog的配置而已，其他配置只是参考，无关cronolog的。
检查
配置完成后检查配置文件是否正常
/app/server/httpd/bin/apachectl -t
Syntax OK
配置完成后需要完全关闭apache所有进程后再启动
service httpd stop
ps -ef|grep httpd
service httpd start
其实所有的系统操作都应该是谨慎而彻底的，确认上一步进行无误后方可进行下一步操作。
检查cronolog运行情况
ps -ef|grep cronolog
root 1006 1 0 Feb04 ?00:00:01 crond
root 22511 5290 0 15:51 ?00:00:00 /usr/sbin/cronolog /app/server/httpd/logs/wifi-www.luckygz.com_1234-error_%Y%m%d.log
root 22512 5290 0 15:51 ?00:00:00 /usr/sbin/cronolog /app/server/httpd/logs/test.com-error_%Y%m%d.log
root 22513 5290 0 15:51 ?00:00:00 /usr/sbin/cronolog /app/server/httpd/logs/test.com_%Y%m%d.log
检查日志是否开始分割
ls -lh /app/server/httpd/logs/|grep 'test.com'
1.正常情况下日志会按照配置进行分割，例如我这里是test.com_20150215.log
2.重启apache后，要有web请求访问网站，新的日志才会生成，不然的话是看不到效果的，虽然配置已经生效
3.原来的test.com.log还是会存在，你可以保留或者删掉
至此完成基本配置，基本实现需求。
more
但这里还想做多一步，就是日志分割了也依然比较大，因为纯文本很大，所以需要做定期压缩
#!/bin/bash
log_dir='/app/server/httpd/logs'
days='5'
log_bak_dir='/app/server/httpd/logs/bak'
find ${log_dir} -name "*.log" -type f -mtime +${days}|grep -v 'bak' |xargs -I '{}' mv '{}' ${log_bak_dir}
cd ${log_bak_dir}
for i in `ls -1 ${log_bak_dir}`
do
gzip $i
done
脚本使用了find和一个for循环来完成，最终的效果就自动将匹配条件的日志文件转移到指定目录，然后进行压缩。
BTW顺带说说
apache默认日志的cronolog配置
cat /app/server/httpd/conf/httpd.conf
ErrorLog "|/usr/sbin/cronolog /app/server/httpd/logs/error_log"
CustomLog "|/usr/sbin/cronolog /app/server/httpd/logs/access_log" common
默认的httpd.conf全局日志error_log 和 access_log是不可以直接使用相对路径来进行分割的，所以需要写全路径，如上。
科普时间
cronolog的配置非常简单，可以在apache里直接调用，使用方法也很简便，直接写时间就可以指定时间分割，下面做了一些解释和例子参考。
cronolog is intended to be used in conjunction with a Web server, such as Apache to split the access log into daily or monthly logs. For example the Apache configuration directives:
TransferLog "|/usr/sbin/cronolog /www/logs/%Y/%m/%d/access.log"
ErrorLog "|/usr/sbin/cronolog /www/logs/%Y/%m/%d/errors.log"
would instruct Apache to pipe its access and error log messages into separate copies of cronolog, which would create new log files each day in a directory hierarchy structured by date, i.e. on 31 December
1996 messages would be written to
/www/logs/1996/12/31/access.log
/www/logs/1996/12/31/errors.log
after midnight the files
/www/logs/1997/01/01/access.log
/www/logs/1997/01/01/errors.log
而时间的格式是使用strftime function，不过根据介绍，基本能看懂，%是说明符，H代表0-23小时，24小时制，如此类推
Template format
Each character in the template represents a character in the expanded filename, except for date and time format specifiers, which are replaced by their expansion. Format specifiers consist of a ‘%’ fol-
lowed by one of the following characters:
% a literal % character
n a new-line character
t a horizontal tab character
Time fields:
H hour (00..23)
I hour (01..12)
p the locale’s AM or PM indicator
M minute (00..59)
S second (00..61, which allows for leap seconds)
X the locale’s time representation (e.g.: "15:12:47")
Z time zone (e.g. GMT), or nothing if the time zone cannot be determined
Date fields:
a the locale’s abbreviated weekday name (e.g.: Sun..Sat)
A the locale’s full weekday name (e.g.: Sunday .. Saturday)
b the locale’s abbreviated month name (e.g.: Jan .. Dec)
B the locale’s full month name, (e.g.: January .. December)
c the locale’s date and time (e.g.: "Sun Dec 15 14:12:47 GMT 1996")
d day of month (01 .. 31)
j day of year (001 .. 366)
m month (01 .. 12)
U week of the year with Sunday as first day of week (00..53, where week 1 is the week containing the first Sunday of the year)
W week of the year with Monday as first day of week (00..53, where week 1 is the week containing the first Monday of the year)
w day of week (0 .. 6, where 0 corresponds to Sunday)
x locale’s date representation (e.g. today in April in Britain: "13/04/97")
y year without the century (00 .. 99)
Y year with the century (1970 .. 2038)
Other specifiers may be available depending on the C library’s implementation of the strftime function.
原文链接：http://www.godblessyuan.com/2015/02/15/apache_cronolog_log_split_rollback/