Index for Section 3

Alphabetical listing for S

Bottom of page

syslog(3)
NAME
  closelog, openlog, setlogmask, syslog, closelog_r, openlog_r, setlogmask_r,
  syslog_r - Control system log

SYNOPSIS
  #include <syslog.h>

  void closelog(
	  void );

  void openlog(
	  const char *id,
	  int log_option,
	  int facility );

  int setlogmask(
	  int mask_priority );

  void syslog(
	  int priority,
	  const char *format, ... );

  void closelog_r(
	  struct syslog_data *syslog_data );

  int openlog_r(
	  const char *id,
	  int log_option,
	  int facility,
	  struct syslog_data *syslog_data );

  int setlogmask_r(
	  int mask_priority,
	  struct syslog_data *syslog_data );

  int syslog_r(
	  int priority,
	  struct syslog_data *syslog_data,
	  const char *format, ... );

  The following function declarations do not conform to current standards and
  are supported only for backward compatibility.

  int openlog(
	  const char *id,
	  int log_option,
	  int facility );

  int syslog(
	  int priority,
	  const char *format, ... );

LIBRARY
  Standard C Library (libc)

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  closelog(), openlog(), setlogmask(), syslog():  XSH4.2

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  id  Specifies a string that is attached to the beginning of every message.

  log_option
      Specifies logging options. Values of the log_option parameter include:

  LOG_PID
      Logs the process ID with each message. This option is useful for
      identifying daemons.

  LOG_CONS
      Sends messages to the console if unable to send them to syslogd. This
      option is useful in daemon processes that have no controlling terminal.

  LOG_NDELAY
      Opens the connection to syslogd immediately, instead of when the first
      message is logged. This option is useful for programs that need to
      manage the order in which file descriptors are allocated.

      [Tru64 UNIX]  This option is required for programs using the chroot
      system call.

  LOG_ODELAY
      Delays opening the connection until syslog() is called.

  LOG_NOWAIT
      Logs messages to the console without waiting for child processes that
      are forked. Use this option for processes that enable notification of
      termination of child processes through SIGCHLD; otherwise, the syslog()
      function may block, waiting for a child process whose exit status has
      already been collected.

  facility
      Specifies the facility that generated the message, which is one of the
      following:

  LOG_KERN
      [Tru64 UNIX]  Messages generated by the kernel. These cannot be
      generated by any user processes.

  LOG_USER
      Messages generated by user processes. This is the default facility when
      none is specified.

  LOG_MAIL
      [Tru64 UNIX]  Messages generated by the mail system.

  LOG_DAEMON
      [Tru64 UNIX]  Messages generated by system daemons.

  LOG_AUTH
      [Tru64 UNIX]  Messages generated by the authorization system: login,
      su, and so on.

  LOG_LPR
      [Tru64 UNIX]  Messages generated by the line printer spooling system.

  LOG_RFS
      [Tru64 UNIX]  Messages generated by remote file systems.

  LOG_LOCAL0 through LOG_LOCAL7
      Reserved for local use.

      This parameter encodes a default facility from the previous list to be
      assigned to messages that do not have an explicit facility encoded.

  priority
      Messages are tagged with codes indicating the type of priority for
      each.  The priority parameter is encoded as a facility (as previously
      listed), which describes the part of the system generating the message,
      and as a level, which indicates the severity of the message. The level
      of severity is selected from the following list:

  LOG_EMERG
      A panic condition was reported to all users.

  LOG_ALERT
      Specifies a condition to be corrected immediately, for example, a
      corrupted database.

  LOG_CRIT
      Specifies a critical conditions, for example, hard device errors.

  LOG_ERR
      Specifies errors.

  LOG_WARNING
      Specifies warning messages.

  LOG_NOTICE
      Specifies that it is not an error condition, but a condition requiring
      special handling.

  LOG_INFO
      Specifies general information messages.

  LOG_DEBUG
      Specifies messages containing information useful in debugging a
      program.

  format [value...]
      Similar to the printf fmt string, with the difference that %m is
      replaced by the current error message obtained from errno.  A trailing
      newline can be added to the message if needed. The value parameters are
      the same as the value parameters of the printf() function. Callers of
      syslog() must ensure that the message is not longer than LINE_MAX
      bytes. Results are unspecified if syslog() is called with a message
      larger than LINE_MAX bytes.

  mask_priority
      Specifies a bit mask used to set the new log priority mask and return
      the previous mask.  The LOG_MASK and LOG_UPTO macros in the
      sys/syslog.h file are used to create the priority mask.

  syslog_data
      [Tru64 UNIX]  The closelog_r(), openlog_r(), setlogmask_r(), and
      syslog_r() functions use this opaque structure.

DESCRIPTION
  The syslog() function writes messages to the system log maintained by the
  syslogd daemon.

  The syslogd daemon reads messages and writes them to the system console or
  to a log file, or forwards them to the syslogd daemon on the appropriate
  host.

  If the syslog() function cannot pass the message to syslogd, it writes the
  message on /dev/console, provided the LOG_CONS option is set.

  If special processing is required, the openlog() function can be used to
  initialize the log file.

  [Tru64 UNIX]	If a program is using the chroot system call, the syslog
  routine will not work correctly unless the program calls the openlog or
  openlog_r routine prior to making the call to chroot .

  The closelog() function closes the log file.

  The setlogmask() function uses the bit mask in the mask_priority parameter
  to set the new log priority mask and returns the previous mask. Logging is
  enabled for the levels indicated by the bits in the mask that are set and
  is disabled where the bits are not set.  The default mask allows all
  priorities to be logged. If the syslog() function is called with a priority
  mask that does not allow logging of that level of message, then the
  function returns without logging the message.

  The log_option, facility, and priority macros are defined in the
  <sys/syslog_pri.h> file.

NOTES
  [Tru64 UNIX]	The closelog_r(), openlog_r, syslog_r, and setlogmask_r
  functions use the syslog_data structure to maintain syslog access state.
  They can be used in place of closelog(), openlog(), syslog(), and
  setlogmask() when it is necessary to have a unique set of IDs, options,
  facilities, or masks for each thread in a multithreaded application. The
  data object syslog_data should be initialized to SYSLOG_DATA_INIT.

RETURN VALUES
  [XSH4.2]  The setlogmask() function returns the previous log priority mask.
  The closelog(), openlog(), and syslog() functions return no value.

  [Tru64 UNIX]	The backward-compatible version of the syslog() function
  returns a value of -1 if either the priority mask excludes this message
  from being logged, or if an error occurs and it is impossible to send the
  message to the syslogd daemon or to the system console.

  [Tru64 UNIX]	Upon successful completion, the backward-compatible version
  of the openlog() function returns a value of 0 (zero).  Otherwise, a value
  of -1 is returned and errno is set to indicate the error.

SEE ALSO
  Functions: profil(2)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for S

Top of page