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

SYNOPSIS

       #include <syslog.h>

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

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

       #include <varargs.h>
       vsyslog(priority, message, args)
       int priority;
       char *message;
       va_list args;

       closelog()

       setlogmask(maskpri)

DESCRIPTION

       Syslog arranges to write message onto the system log main-
       tained  by  syslogd(8).  The message is tagged with prior-
       ity.  The message looks like  a  printf(3)  string  except
       that  %m is replaced by the current error message (as ref-
       erenced by errno).  A trailing newline is added if needed.
       An  alternate  form,  in  which the arguments have already
       been captured using the variable-length  argument  facili-
       ties of varargs(3), is available under the name vsyslog.

       This message will be read by syslogd(8) and written to the
       system console, log files,  or  forwarded  to  syslogd  on
       another host as appropriate.

       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_ALERT
              A  condition  that should be corrected immediately,
              such as a corrupted system database.

       LOG_CRIT
              Critical conditions, e.g., hard device errors.

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

              A  panic  condition.  This is normally broadcast to
              all users.

       LOG_ERR
              Errors.

       LOG_INFO
              Informational messages.

       LOG_NOTICE
              Conditions  that  are  not  error  conditions,  but
              should possibly be handled specially.

       LOG_WARNING
              Warning messages.

       If  syslog  cannot  pass  the  message to syslogd, it will
       attempt to write the message to the  console  (``/dev/con-
       sole'') if the LOG_CONS option is set (see below).

       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.   Current  values  for  logopt
       are:

       LOG_CONS
              If  unable to send the message to syslogd, write it
              to the console.

       LOG_NDELAY
              Open the connection to syslogd  immediately.   Nor-
              mally  the  open is delayed until the first message
              is logged.  Useful for programs that need to manage
              the  order in which file descriptors are allocated.

       LOG_PERROR
              Write the message to stderr as well to  the  system
              log.

       LOG_PID
              Log  the  process  id with each message: useful for
              identifying instantiations of daemons.

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

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

              The clock daemon.

       LOG_DAEMON
              System  daemons,  such  as ftpd(8), routed(8), etc,
              that are  not  provided  for  explicitly  by  other
              facilities.

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

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

       LOG_MAIL
              The mail system.

       LOG_NEWS
              The network news system.

       LOG_SYSLOG
              Messages generated internally by syslogd(8).

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

       LOG_UUCP
              The uucp system.

       LOG_LOCAL0
              Reserved  for  local use.  Similarly for LOG_LOCAL1
              through LOG_LOCAL7.

       Closelog can be used to close the log file.

       Setlogmask sets the  log  priority  mask  to  maskpri  and
       returns  the previous mask.  Calls to syslog with a prior-
       ity 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

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

       openlog("ftpd", LOG_PID, LOG_DAEMON);
       setlogmask(LOG_UPTO(LOG_ERR));
       syslog(LOG_INFO, "Connection from host %d", CallingHost);

SEE ALSO

       logger(1), syslogd(8)