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SYSLOG(3)                  Library Functions Manual                  SYSLOG(3)



NAME
       syslog, openlog, closelog, setlogmask - control system log

SYNOPSIS
       #include <&lt;syslog.h>&gt;

       openlog(ident, logopt, facility)
       char *ident;

       syslog(priority, message, parameters ... )
       char *message;

       closelog()

       setlogmask(maskpri)

DESCRIPTION
       syslog()  passes message to syslogd(8), which logs it in an appropriate
       system log, writes it to the system console, forwards it to a  list  of
       users,  or forwards it to the syslogd on another host over the network.
       The message is tagged with a priority of priority.  The  message  looks
       like  a  printf(3V)  string  except  that %m is replaced by the current
       error message (collected from errno).  A trailing NEWLINE is  added  if
       needed.

       Priorities  are  encoded  as  a  facility  and  a  level.  The facility
       describes the part of the system generating the message.  The level  is
       selected from an ordered list:

              LOG_EMERG           A  panic condition.  This is normally broad-
                                  cast to all users.

              LOG_ALERT           A condition that should be corrected immedi-
                                  ately, such as a corrupted system database.

              LOG_CRIT            Critical  conditions,  such  as  hard device
                                  errors.

              LOG_ERR             Errors.

              LOG_WARNING         Warning messages.

              LOG_NOTICE          Conditions that are  not  error  conditions,
                                  but that may require special handling.

              LOG_INFO            Informational messages.

              LOG_DEBUG           Messages  that  contain information normally
                                  of use only when debugging a program.

       If special processing is needed, openlog() can be called to  initialize
       the  log  file.   The  parameter ident is a string that is prepended to
       every message.  logopt is a bit field indicating logging options.  Cur-
       rent values for logopt are:

              LOG_PID             Log  the process ID with each message.  This
                                  is useful for  identifying  specific  daemon
                                  processes (for daemons that fork).

              LOG_CONS            Write messages to the system console if they
                                  cannot be sent to syslogd.  This  option  is
                                  safe to use in daemon processes that have no
                                  controlling terminal, since  syslog()  forks
                                  before opening the console.

              LOG_NDELAY          Open  the connection to syslogd immediately.
                                  Normally the open is delayed until the first
                                  message  is logged.  This is useful for pro-
                                  grams that need to manage the order in which
                                  file descriptors are allocated.

              LOG_NOWAIT          Do  not  wait  for child processes that have
                                  been forked to log messages  onto  the  con-
                                  sole.   This  option  should be used by pro-
                                  cesses that  enable  notification  of  child
                                  termination  using  SIGCHLD,  since syslog()
                                  may otherwise  block  waiting  for  a  child
                                  whose  exit  status  has  already  been col-
                                  lected.

       The facility parameter encodes a default facility to be assigned to all
       messages that do not have an explicit facility already encoded:

              LOG_KERN            Messages  generated  by  the  kernel.  These
                                  cannot be generated by any user processes.

              LOG_USER            Messages generated by random user processes.
                                  This  is  the default facility identifier if
                                  none is specified.

              LOG_MAIL            The mail system.

              LOG_DAEMON          System   daemons,    such    as    ftpd(8C),
                                  routed(8C), etc.

              LOG_AUTH            The  authorization system: login(1), su(1V),
                                  getty(8), etc.

              LOG_LPR             The line printer  spooling  system:  lpr(1),
                                  lpc(8), lpd(8), etc.

              LOG_NEWS            Reserved for the USENET network news system.

              LOG_UUCP            Reserved  for  the  UUCP system; it does not
                                  currently use syslog.

              LOG_CRON            The  cron/at  facility;  crontab(1),  at(1),
                                  cron(8), etc.

              LOG_LOCAL0-7        Reserved for local use.

       closelog() can be used to close the log file.

       setlogmask() sets the log priority mask to maskpri and returns the pre-
       vious mask.  Calls to syslog() with a priority not set in  maskpri  are
       rejected.  The mask for an individual priority pri is calculated by the
       macro LOG_MASK(pri); the mask for all priorities up  to  and  including
       toppri  is given by the macro LOG_UPTO(toppri).  The default allows all
       priorities to be logged.

EXAMPLES
       This call logs a message at priority LOG_ALERT:

              syslog(LOG_ALERT, "who: internal error 23");

       The FTP daemon ftpd would make this call to openlog() to indicate  that
       all  messages it logs should have an identifying string of ftpd, should
       be treated by syslogd as other messages from system daemons are, should
       include the process ID of the process logging the message:

              openlog("ftpd", LOG_PID, LOG_DAEMON);

       Then  it would make the following call to setlogmask() to indicate that
       messages at priorities from LOG_EMERG through LOG_ERR should be logged,
       but that no messages at any other priority should be logged:

              setlogmask(LOG_UPTO(LOG_ERR));

       Then,  to log a message at priority LOG_INFO, it would make the follow-
       ing call to syslog:

              syslog(LOG_INFO, "Connection from host %d", CallingHost);

       A locally-written utility could use the following call to  syslog()  to
       log  a  message  at priority LOG_INFO to be treated by syslogd as other
       messages to the facility LOG_LOCAL2 are:

              syslog(LOG_INFO|LOG_LOCAL2, "error: %m");

SEE ALSO
       at(1), crontab(1), logger(1),  login(1),  lpr(1),  su(1V),  printf(3V),
       syslog.conf(5),    cron(8),   ftpd(8C),   getty(8),   lpc(8),   lpd(8),
       routed(8C), syslogd(8)



                               22 November 1987                      SYSLOG(3)