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[root@www ~]# vim /etc/logrotate.conf

# 底下的設定是 "logrotate 的預設設定值" ，如果個別的檔案設定了其他的參數，
# 則將以個別的檔案設定為主，若該檔案沒有設定到的參數則以這個檔案的內容為預設值！

weekly    <==預設每個禮拜對登錄檔進行一次 rotate 的工作
rotate 4  <==保留幾個登錄檔呢？預設是保留四個！
create    <==由於登錄檔被更名，因此建立一個新的來繼續儲存之意！
#compress <==被更動的登錄檔是否需要壓縮？如果登錄檔太大則可考慮此參數啟動

include /etc/logrotate.d
# 將 /etc/logrotate.d/ 這個目錄中的所有檔案都讀進來執行 rotate 的工作！

/var/log/wtmp {       <==僅針對 /var/log/wtmp 所設定的參數
    monthly           <==每個月一次，取代每週！
    minsize 1M        <==檔案容量一定要超過 1M 後才進行 rotate (略過時間參數)
    create 0664 root utmp <==指定新建檔案的權限與所屬帳號/群組
    rotate 1          <==僅保留一個，亦即僅有 wtmp.1 保留而已。
}
# 這個 wtmp 可記錄登入者與系統重新開機時的時間與來源主機及登入期間的時間。
# 由於具有 minsize 的參數，因此不見得每個月一定會進行一次喔！要看檔案容量。
# 由於僅保留一個登錄檔而已，不滿意的話可以將他改成 rotate 5 吧！

[root@www ~]# vi /etc/logrotate.d/syslog
/var/log/messages /var/log/secure /var/log/maillog /var/log/spooler \
/var/log/boot.log /var/log/cron {
  sharedscripts
  postrotate
    /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    /bin/kill -HUP `cat /var/run/rsyslogd.pid 2> /dev/null` 2> /dev/null || true
  endscript
}

[root@www ~]# vi /etc/logrotate.d/syslog
/var/log/messages /var/log/secure /var/log/maillog /var/log/spooler \
/var/log/boot.log /var/log/cron {
  sharedscripts
  prerotate
    /usr/bin/chattr -a /var/log/messages
  endscript
  sharedscripts
  postrotate
    /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    /bin/kill -HUP `cat /var/run/rsyslogd.pid 2> /dev/null` 2> /dev/null || true
    /usr/bin/chattr +a /var/log/messages
  endscript
}

[root@www ~]# logrotate [-vf] logfile

[root@www ~]# logrotate -v /etc/logrotate.conf
reading config file /etc/logrotate.conf <==讀取主要設定檔
including /etc/logrotate.d              <==呼叫外部的設定
reading config file acpid               <==就是外部設定啊！
....(中間省略)....
Handling 21 logs                        <==共有 21 個登錄檔被記錄
....(中間省略)....
rotating pattern: /var/log/messages /var/log/secure /var/log/maillog \
/var/log/spooler /var/log/boot.log /var/log/cron  weekly (4 rotations)
empty log files are rotated, old logs are removed
considering log /var/log/messages       <==開始處理 messages
  log does not need rotating            <==因為時間未到，不需要更動！
....(底下省略)....

[root@www ~]# logrotate -vf /etc/logrotate.conf
....(前面省略)....
rotating log /var/log/messages, log->rotateCount is 4
renaming /var/log/messages.4 to /var/log/messages.5 (rotatecount 4, logstart 1, i 4),
renaming /var/log/messages.3 to /var/log/messages.4 (rotatecount 4, logstart 1, i 3),
renaming /var/log/messages.2 to /var/log/messages.3 (rotatecount 4, logstart 1, i 2),
renaming /var/log/messages.1 to /var/log/messages.2 (rotatecount 4, logstart 1, i 1),
renaming /var/log/messages.0 to /var/log/messages.1 (rotatecount 4, logstart 1, i 0),
old log /var/log/messages.0 does not exist
....(底下省略)....
# 看到否？整個 rotate 的動作就是這樣一步一步進行的～

[root@www ~]# ll /var/log/messages*; lsattr /var/log/messages
-rw------- 1 root root    63 Apr  8 15:19 /var/log/messages
-rw------- 1 root root   670 Apr  8 14:22 /var/log/messages.1
-rw------- 1 root root 24984 Apr  1 19:26 /var/log/messages.2
-rw------- 1 root root  1911 Mar 28 11:32 /var/log/messages.3
-rw------- 1 root root 25193 Mar 22 04:02 /var/log/messages.4
-----a------- /var/log/messages <==主動加入 a 的隱藏屬性囉！

[root@www ~]# chattr +a /var/log/admin.log
[root@www ~]# lsattr /var/log/admin.log
-----a------- /var/log/admin.log
[root@www ~]# mv /var/log/admin.log /var/log/admin.log.1
mv: cannot move `/var/log/admin.log' to `/var/log/admin.log.1':
Operation not permitted
# 這裡確定了加入 a 的隱藏屬性！所以 root 無法移動此登錄檔！

# 2. 開始建立 logrotate 的設定檔，增加一個檔案在 /etc/logrotate.d 內就對了！
[root@www ~]# vi /etc/logrotate.d/admin
# This configuration is from VBird 2009/04/08
/var/log/admin.log {
        monthly   <==每個月進行一次
        size=10M  <==檔案容量大於 10M 則開始處置
        rotate 5  <==保留五個！
        compress  <==進行壓縮工作！
        sharedscripts
        prerotate
                /usr/bin/chattr -a /var/log/admin.log
        endscript
        sharedscripts
        postrotate
                /usr/bin/killall -HUP syslogd
                /usr/bin/chattr +a /var/log/admin.log
        endscript
}

# 3. 測試一下 logrotate 相關功能的資訊顯示：
[root@www ~]# logrotate -v /etc/logrotate.conf
....(前面省略)....
rotating pattern: /var/log/admin.log  10485760 bytes (5 rotations)
empty log files are rotated, old logs are removed
considering log /var/log/admin.log
  log does not need rotating
not running prerotate script, since no logs will be rotated
not running postrotate script, since no logs were rotated
....(底下省略)....
# 因為還不足一個月，檔案也沒有大於 10M，所以不需進行輪替！

# 4. 測試一下強制 logrotate 與相關功能的資訊顯示：
[root@www ~]# logrotate -vf /etc/logrotate.d/admin
reading config file /etc/logrotate.d/admin
reading config info for /var/log/admin.log

Handling 1 logs

rotating pattern: /var/log/admin.log  forced from command line (5 rotations)
empty log files are rotated, old logs are removed
considering log /var/log/admin.log
  log needs rotating
rotating log /var/log/admin.log, log->rotateCount is 5
renaming /var/log/admin.log.5.gz to /var/log/admin.log.6.gz (rotatecount 5, logstart 1, i 5),
old log /var/log/admin.log.5.gz does not exist
renaming /var/log/admin.log.4.gz to /var/log/admin.log.5.gz (rotatecount 5, logstart 1, i 4),
old log /var/log/admin.log.4.gz does not exist
renaming /var/log/admin.log.3.gz to /var/log/admin.log.4.gz (rotatecount 5, logstart 1, i 3),
old log /var/log/admin.log.3.gz does not exist
renaming /var/log/admin.log.2.gz to /var/log/admin.log.3.gz (rotatecount 5, logstart 1, i 2),
old log /var/log/admin.log.2.gz does not exist
renaming /var/log/admin.log.1.gz to /var/log/admin.log.2.gz (rotatecount 5, logstart 1, i 1),
old log /var/log/admin.log.1.gz does not exist
renaming /var/log/admin.log.0.gz to /var/log/admin.log.1.gz (rotatecount 5, logstart 1, i 0),
old log /var/log/admin.log.0.gz does not exist
log /var/log/admin.log.6.gz doesn't exist -- won't try to dispose of it
running prerotate script
renaming /var/log/admin.log to /var/log/admin.log.1
running postrotate script
compressing log with: /bin/gzip


[root@www ~]# lsattr /var/log/admin.log*
-----a------- /var/log/admin.log
------------- /var/log/admin.log.1.gz  <==有壓縮過喔！