UNIX class systems provide system-wide log service support: syslogd. Syslogd is read when reading the configuration file /etc/syslog.conf. Each row of syslog.conf (# 开 的 开 注, will be ignored) consisting of "Selector action".
The selection is "facility. Priority" (facility.priority). The names of the amenities and priority are the standard names provided by the system.
Facility:
KERN 0 kernel log message
User 1 Random User Log Message
Mail 2 Mail System Log Message
Daemon 3 system daemon log message
Auth 4 Security Management Log Message
Syslog 5 syslogd itself log message
LPR 6 printer log message
News 7 News Service Log Message
UUCP 8 UUCP System Log Message
Cron 9 system always daemon log messages
Authpriv 10 private security management log message
FTP 11 FTP daemon log message
12 ~ 15 Reserved for system use
Local0 ~ Local7 16 ~ 23 is reserved for local use
Priority, the lower the situation, the more serious:
Emerg 0 system is not available
Alert 1 must take an event immediately
CRIT 2 Key Events
Err 3 error event
WARNING 4 Warning Event
NOTICE 5 ordinary but important events
INFO 6 useful information
Debug 7 debugging information
You can use * to indicate any facility (*) or any priority (* after the period). Specifies a priority to a log message greater than or equal to the priority. You can use none to indicate that no priority is included.
Linux has made some extensions to the Syslog of BSD, introduced to '=' and '!'. You can use '=' before any priority, indicating that only the priority is greater than its priority. '!' Indicates that the reversion can be placed in front of the priority or '=' (if any), indicating that it means to the opposite. Several facilities with the same priority can be written together in front of the period, separated by ','. A plurality of selectors having the same action can be written in the selective field of the same row, and each selector is separated from ';' separate.
A legal selector is some cases (for example):
1, *. *: Any priority log message for any facility
1, local0. *: Any priority log message for local0
2, *. CRIT Any facility priority is greater than log messages for key events
3, *. = Cries for any facility key event log message
4, *. *; Kern.none Any log message in any other facility except Kern
5, kern.info; kern.! ERR KERN facility from INFO to WARNING log message
Action domain describes abstract nouns "logfile", a "logfile" does not have to be a real file. Syslogd provides the following action:
1. Normal files, describe the full path name of the file. The path name before adding '-' means ignoring the synchronization file.
2, named the pipe (FIFO). In order to write a full path of the file that represents a named pipe, "|" means writing the log into a naming pipe.
3, terminals and consoles. Such as / dev / console.
4, remote machine. "@Hostname"
5, list of users
6. All users logged in. Use *.
Log function:
Void OpenLog (Char * Ideen, Int Option, Int Facility)
Void Syslog (int priority, char * format);
Log message format:
In order to use the powerful log feature provided by Syslogd, you can use these log functions in the log system.
In OpenLog, Option generally takes 0, the facility is these defined above, but with the following constants:
LOG_AUTH AUTH
LOG_AUTHPRIV Authpriv
Log_cron cron
Log_daemon daemon
LOG_KERN KERN
LOG_LOCAL0 ~ LOG_LOCAL7 LOCAL0 ~ LOCAL7
LOG_LPR LPR
LOG_MAIL MAIL
LOG_NEWS NEWS
LOG_SYSLOG SYSLOG
Log_User User
LOG_UUCP UUCP
Priority in the syslog () function is the priorities mentioned above, here the following constant is used
LOG_EMERG EMERG
LOG_ALERT ALERT
Log_crit critlog_err ERR
Log_Warning Warning
LOG_NOTICE NOTICE
LOG_INFO INFO
LOG_DEBUG Debug
The Format in syslog () is the same as Printf (Char * Format).
For example, you can use OpenLog in the IKE module ("IKE", 0, LOG_LOCAL0)
Then when you need to do logs, such as encrypted cards, you are faulty:
Syslog (log_emerg, "sjy01-a cipher crash!");
