linux - syslog (3)

       closelog() closes the descriptor being used  to  write  to
       the system logger. The use of closelog() is optional.

       openlog()  opens  a  connection to the system logger for a
       program. The string pointed to by ident is added  to  each
       message,  and is typically set to the program name. Values
       for option and facility are given in the next section. The
       use  of  openlog()  is  optional; It will automatically be
       called by syslog() if necessary, in which case ident  will
       default to NULL.

       syslog()  generates  a  log  message,  which  will be dis-
       tributed by syslogd(8).  priority is a combination of  the
       facility  and the level, values for which are given in the
       next section. The remaining arguments are a format , as in
       printf(3) and any arguments required by the format, except
       that the two character %m will be replaced  by  the  error
       message  string  (strerror)  corresponding  to the present
       value of errno.

       This section list the parameters used to set the values of
       option, facility, and priority.

   option
       The option argument to openlog() is an OR of any of these:

       LOG_CONS
            write directly to system console if there is an error
            while sending to system logger

       LOG_NDELAY
            open  the  connection immediately (normally, the con-
            nection is opened when the first message is logged)

       LOG_PERROR
       LOG_PID
            include PID with each message

   facility
       The facility argument is used to specify what type of pro-
       gram  is logging the message.  This lets the configuration
       file specify that messages from different facilities  will
       be handled differently.

       LOG_AUTH
              security/authorization   messages  (DEPRECATED  Use
              LOG_AUTHPRIV instead)

       LOG_AUTHPRIV
              security/authorization messages (private)

       LOG_CRON
              clock daemon (cron and at)

       LOG_DAEMON
              other system daemons

       LOG_KERN
              kernel messages

       LOG_LOCAL0 through LOG_LOCAL7
              reserved for local use

       LOG_LPR
              line printer subsystem

       LOG_MAIL
              mail subsystem

       LOG_NEWS
              USENET news subsystem

       LOG_SYSLOG
              messages generated internally by syslogd

       LOG_USER(default)
              generic user-level messages

       LOG_UUCP
              UUCP subsystem


   level
       This determines the importance of the message. The  levels
       are, in order of decreasing importance:

       LOG_EMERG
       LOG_ALERT
              action must be taken immediately

       LOG_CRIT
              critical conditions

       LOG_ERR
              error conditions

       LOG_WARNING
              warning conditions

       LOG_NOTICE
              normal, but significant, condition

       LOG_INFO
              informational message

       LOG_DEBUG
              debug-level message

       A syslog function call appeared in BSD 4.2.

       logger(1), syslog.conf(5), syslogd(8)