linux系統自動的log功能，目前由rsyslog服務代管，應該說rsyslog 是syslog 的升級版。

[[email protected] ~]# cat /etc/rsyslog.conf
# rsyslog configuration file

#### MODULES ####
#載入模組列表

# The imjournal module bellow is now used as a message source instead of imuxsock.
$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
提供對本地系統日誌的支援
$ModLoad imjournal # provides access to the systemd journal
提供對systemd日誌的訪問
#$ModLoad imklog # reads kernel messages (the same are read from journald)
讀取核心訊息
#$ModLoad immark  # provides --MARK-- message capability
提供--MARK--訊息功能

# Provides UDP syslog reception
#$ModLoad imudp
#$UDPServerRun 514  允許514埠接收使用UDP協議轉發過來的日誌

# Provides TCP syslog reception
#$ModLoad imtcp
#$InputTCPServerRun 514允許514埠接收使用TCP協議轉發過來的日誌


#### GLOBAL DIRECTIVES ####
#全域性指令，
# Where to place auxiliary files
$WorkDirectory /var/lib/rsyslog

# Use default timestamp format  定義日誌格式預設模板 
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat

# File syncing capability is disabled by default. This feature is usually not required,
# not useful and an extreme performance hit
#$ActionFileEnableSync on

# Include all config files in /etc/rsyslog.d/
$IncludeConfig /etc/rsyslog.d/*.conf

# Turn off message reception via local log socket;
# local messages are retrieved through imjournal now.
$OmitLocalLogging on

# File to store the position in the journal
$IMJournalStateFile imjournal.state


#### RULES ####
#規則
# Log all kernel messages to the console.
# Logging much else clutters up the screen.
#kern.*                                                 /dev/console
關於核心的所有日誌都放到/dev/console(控制檯)

# Log anything (except mail) of level info or higher.
# Don't log private authentication messages!
*.info;mail.none;authpriv.none;cron.none                /var/log/messages
記錄所有日誌型別的info級別以及大於info級別的資訊到/var/log/messages，但是mail郵件資訊，authpriv驗證方面的資訊和cron時間任務相關的資訊除外

# The authpriv file has restricted access.
authpriv.*                                              /var/log/secure
authpriv驗證相關的所有資訊存放在/var/log/secure

# Log all the mail messages in one place.
mail.*                                                  -/var/log/maillog
郵件的所有資訊存放在/var/log/maillog; 這裡有一個-符號, 表示是使用非同步的方式記錄, 因為日誌一般會比較大

# Log cron stuff
cron.*                                                  /var/log/cron
計劃任務有關的資訊存放在/var/log/cron

# Everybody gets emergency messages
*.emerg                                                 :omusrmsg:*
 記錄所有的大於等於emerg級別資訊, 以wall方式傳送給每個登入到系統的人

# Save news errors of level crit and higher in a special file.
uucp,news.crit                                          /var/log/spooler
記錄uucp,news.crit等存放在/var/log/spooler
uucp  –unix to unix copy, unix主機之間相關的通訊，news   –新聞組

# Save boot messages also to boot.log
local7.*                                                /var/log/boot.log
啟動的相關資訊

#### begin forwarding rule ###
 轉發規則
# The statement between the begin ... end define a SINGLE forwarding
# rule. They belong together, do NOT split them. If you create multiple
# forwarding rules, duplicate the whole block!  
# Remote Logging (we use TCP for reliable delivery)
# An on-disk queue is created for this action. If the remote host is
# down, messages are spooled to disk and sent when it is up again.
#$ActionQueueFileName fwdRule1 # unique name prefix for spool files
#$ActionQueueMaxDiskSpace 1g   # 1gb space limit (use as much as possible)
#$ActionQueueSaveOnShutdown on # save messages to disk on shutdown
#$ActionQueueType LinkedList   # run asynchronously
#$ActionResumeRetryCount -1    # infinite retries if host is down
# remote host is: name/ip:port, e.g. 192.168.0.1:514, port optional
#*.* @@remote-host:514  
@@表示通過tcp協議傳送，使用TCP協議轉發到remote-host的514(預設)埠
@表示通過udp進行轉發
# ### end of the forwarding rule ###