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CLOSELOG(P)                                                        CLOSELOG(P)



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

SYNOPSIS
       #include <syslog.h>

       void closelog(void);
       void openlog(const char *ident, int logopt, int facility);
       int setlogmask(int maskpri);
       void syslog(int priority, const char *message, ... /* arguments */);


DESCRIPTION
       The  syslog()  function  shall  send a message to an implementation-defined logging
       facility, which may log it in an implementation-defined system log, write it to the
       system  console, forward it to a list of users, or forward it to the logging facil-
       ity on another host over the network. The logged message shall  include  a  message
       header  and  a message body. The message header contains at least a timestamp and a
       tag string.

       The message body is generated from the message and following arguments in the  same
       manner  as  if these were arguments to printf(), except that the additional conver-
       sion specification %m shall be recognized; it shall  convert  no  arguments,  shall
       cause  the output of the error message string associated with the value of errno on
       entry to syslog(), and may be mixed with argument specifications of the "%n$" form.
       If a complete conversion specification with the m conversion specifier character is
       not just %m , the behavior is undefined. A  trailing  <newline>  may  be  added  if
       needed.

       Values  of  the  priority  argument  are formed by OR’ing together a severity-level
       value and an optional facility value. If no facility value is specified,  the  cur-
       rent default facility value is used.

       Possible values of severity level include:

       LOG_EMERG
              A panic condition.

       LOG_ALERT
              A condition that should be corrected immediately, 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  han-
              dling.

       LOG_INFO
              Informational messages.

       LOG_DEBUG
              Messages that contain information normally of use only when debugging a pro-
              gram.


       The facility indicates the application or system component generating the  message.
       Possible facility values include:

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

       LOG_LOCAL0
              Reserved for local use.

       LOG_LOCAL1
              Reserved for local use.

       LOG_LOCAL2
              Reserved for local use.

       LOG_LOCAL3
              Reserved for local use.

       LOG_LOCAL4
              Reserved for local use.

       LOG_LOCAL5
              Reserved for local use.

       LOG_LOCAL6
              Reserved for local use.

       LOG_LOCAL7
              Reserved for local use.


       The openlog() function shall set process attributes that affect subsequent calls to
       syslog().  The  ident  argument is a string that is prepended to every message. The
       logopt argument indicates logging options. Values for logopt are constructed  by  a
       bitwise-inclusive OR of zero or more of the following:

       LOG_PID
              Log  the  process  ID with each message. This is useful for identifying spe-
              cific processes.

       LOG_CONS
              Write messages to the system console if they cannot be sent to  the  logging
              facility.  The  syslog()  function ensures that the process does not acquire
              the console as a controlling terminal in the process of writing the message.

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

       LOG_ODELAY
              Delay open until syslog() is called.

       LOG_NOWAIT
              Do not wait for child processes that may have been created during the course
              of logging the message. This option should be used by processes that  enable
              notification  of  child termination using SIGCHLD, since syslog() may other-
              wise block waiting for a child whose exit status has already been collected.


       The  facility  argument  encodes  a default facility to be assigned to all messages
       that do not have an explicit facility already encoded. The initial default facility
       is LOG_USER.

       The openlog() and syslog() functions may allocate a file descriptor. It is not nec-
       essary to call openlog() prior to calling syslog().

       The closelog() function shall close any open file descriptors allocated by previous
       calls to openlog() or syslog().

       The  setlogmask()  function shall set the log priority mask for the current process
       to maskpri and return the previous mask. If the maskpri argument is 0, the  current
       log  mask is not modified. Calls by the current process to syslog() with a priority
       not set in maskpri shall be rejected.  The default log mask allows  all  priorities
       to be logged. A call to openlog() is not required prior to calling setlogmask().

       Symbolic constants for use as values of the logopt, facility, priority, and maskpri
       arguments are defined in the <syslog.h> header.

RETURN VALUE
       The setlogmask()  function  shall  return  the  previous  log  priority  mask.  The
       closelog(), openlog(), and syslog() functions shall not return a value.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
   Using openlog()
       The  following  example  causes  subsequent calls to syslog() to log the process ID
       with each message, and to write messages to the system console if  they  cannot  be
       sent to the logging facility.


              #include <syslog.h>


              char *ident = "Process demo";
              int logopt = LOG_PID | LOG_CONS;
              int facility = LOG_USER;
              ...
              openlog(ident, logopt, facility);

   Using setlogmask()
       The following example causes subsequent calls to syslog() to accept error messages,
       and to reject all other messages.


              #include <syslog.h>


              int result;
              int mask = LOG_MASK (LOG_ERR);
              ...
              result = setlogmask(mask);

   Using syslog
       The following example sends the message "This is a message" to the default  logging
       facility, marking the message as an error message generated by random processes.


              #include <syslog.h>


              char *message = "This is a message";
              int priority = LOG_ERR | LOG_USER;
              ...
              syslog(priority, message);

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       printf() , the Base Definitions volume of IEEE Std 1003.1-2001, <syslog.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information  Technology  --  Portable  Operating
       System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C)
       2001-2003 by the Institute of Electrical and Electronics  Engineers,  Inc  and  The
       Open  Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard  is
       the   referee   document.   The   original  Standard  can  be  obtained  online  at
       http://www.opengroup.org/unix/online.html .



POSIX                                2003                          CLOSELOG(P)

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