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RedHat 9 (Linux i386) - man page for syslog (redhat section 3)

SYSLOG(3)			    Linux Programmer's Manual				SYSLOG(3)

NAME
       closelog, openlog, syslog - send messages to the system logger

SYNOPSIS
       #include <syslog.h>

       void openlog(const char *ident, int option, int facility);
       void syslog(int priority, const char *format, ...);
       void closelog(void);

       #include <stdarg.h>

       void vsyslog(int priority, const char *format, va_list ap);

DESCRIPTION
       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 prepended to every message, and is typically set to the program name.  The option
       argument specifies flags which control the operation of openlog() and subsequent calls  to
       syslog().   The facility argument establishes a default to be used if none is specified in
       subsequent calls to syslog().  Values for option and facility are given below.  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 distributed by syslogd(8).   The  priority
       argument  is  formed  by  ORing	the facility and the level values (explained below).  The
       remaining arguments are a format, as in printf(3) and any arguments required by	the  for-
       mat,  except  that  the	two  character	sequence %m will be replaced by the error message
       string strerror(errno).	A trailing newline is added when needed.

       The function vsyslog() performs the same task as syslog()  with	the  difference  that  it
       takes  a  set  of arguments which have been obtained using the stdarg(3) variable argument
       list macros.

PARAMETERS
       This section lists the parameters used to set the values of option, facility,  and  prior-
       ity.

   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 log-
	      ger.

       LOG_NDELAY
	      Open the connection immediately (normally, the connection is opened when the  first
	      message is logged).

       LOG_NOWAIT
	      Don't  wait  for	child processes that may have been created while logging the mes-
	      sage.  (The GNU C library does not create a child process, so this  option  has  no
	      effect on Linux.)

       LOG_ODELAY
	      The  converse of LOG_NDELAY; opening of the connection is delayed until syslog() is
	      called.  (This is the default, and need not be specified.)

       LOG_PERROR
	      (Not in SUSv3.) Print to stderr as well.

       LOG_PID
	      Include PID with each message.

   facility
       The facility argument is used to specify what type of  program  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
	      system daemons without separate facility value

       LOG_FTP
	      ftp daemon

       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
	      system is unusable

       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

       The function setlogmask(3) can be used to restrict logging to specified levels only.

CONFORMING TO
       The  functions  openlog(),  closelog(),	and syslog() (but not vsyslog()) are specified in
       SUSv2 and POSIX 1003.1-2001.  POSIX 1003.1-2001 specifies only the LOG_USER and LOG_LOCAL*
       values  for  facility.  However, with the exception of LOG_AUTHPRIV and LOG_FTP, the other
       facility values appear on most Unix systems.  The LOG_PERROR value for option is not spec-
       ified by POSIX 1003.1-2001, but is available in most versions of Unix.

HISTORY
       A  syslog  function  call  appeared  in	BSD  4.2.  BSD 4.3 documents openlog(), syslog(),
       closelog(), and setlogmask().  4.3BSD-Reno also documents vsyslog().  Of course	early  v*
       functions used the <varargs.h> mechanism, which is not compatible with <stdarg.h>.

NOTES
       The parameter ident in the call of openlog() is probably stored as-is. Thus, if the string
       it points to is changed, syslog() may start prepending the  changed  string,  and  if  the
       string it points to ceases to exist, the results are undefined.	Most portable is to use a
       string constant.

       Never pass a string with user-supplied data as a format, use
	      syslog("%s", string);
       instead.

SEE ALSO
       logger(1), setlogmask(3), syslog.conf(5), syslogd(8)

Linux					    2002-01-03					SYSLOG(3)


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