openlog(3) - bsd211

1SYSLOG(3)                  Library Functions Manual                  SYSLOG(3)
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NAME

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

9       #include <syslog.h>
10       #include <varargs.h>
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12       void syslog(priority, message, ...);
13       int priority;
14       char *message;
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16       void vsyslog(priority, message, args);
17       int priority;
18       char *message;
19       va_list args;
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21       void openlog(ident, logopt, facility);
22       char *ident;
23       int logopt;
24       int facility;
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26       void closelog();
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28       int setlogmask(maskpri);
29       int maskpri;
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DESCRIPTION

32       The syslog() function writes message to the system message logger.  The
33       message is then written to the system  console,  log  files,  logged-in
34       users, or forwarded to other machines as appropriate. (See syslogd(8)).
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36       The  message  is identical to a printf(3) format string, except that %m
37       is replaced by the current error message as denoted by the global vari‐
38       able  errno.  See strerror(3)).  A trailing newline is added if none is
39       present.
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41       The vsyslog() function is an alternate form in which the arguments have
42       already  been captured using the variable-length argument facilities of
43       varargs(3).
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45       The message is tagged with  priority.   Priorities  are  encoded  as  a
46       facility  and  a  level.  The facility describes the part of the system
47       generating the message.  The  level  is  selected  from  the  following
48       ordered (high to low) list:
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50       LOG_EMERG       A  panic  condition.  This is normally broadcast to all
51                       users.
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53       LOG_ALERT       A condition that should be corrected immediately,  such
54                       as a corrupted system database.
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56       LOG_CRIT        Critical conditions, e.g., hard device errors.
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58       LOG_ERR         Errors.
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60       LOG_WARNING     Warning messages.
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62       LOG_NOTICE      Conditions  that  are  not error conditions, but should
63                       possibly be handled specially.
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65       LOG_INFO        Informational messages.
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67       LOG_DEBUG       Messages that contain information normally of use  only
68                       when debugging a program.
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70       The  openlog() function provides for more specialized processing of the
71       messages sent by syslog() and vsyslog().   The  parameter  ident  is  a
72       string that will be prepended to every message.  The logopt argument is
73       a bit field specifying logging options, which is formed by  OR'ing  one
74       or more of the following values:
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76       LOG_CONS       If  syslog  cannot  pass  the message to syslogd it will
77                      attempt to write the message to the  console  (/dev/con‐
78                      sole).
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80       LOG_NDELAY     Open  the  connection  to syslogd immediately.  Normally
81                      the open is delayed until the first message  is  logged.
82                      Useful  for  programs  that  need to manage the order in
83                      which file descriptors are allocated.
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85       LOG_PERROR     Write the message to standard error output  as  well  to
86                      the system log.
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88       LOG_PID        Log the process id with each message: useful for identi‐
89                      fying instantiations of daemons.
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91       The facility parameter encodes a default facility to be assigned to all
92       messages that do not have an explicit facility encoded:
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94       LOG_AUTH       The  authorization  system:  login(1),  su(1), getty(8),
95                      etc.
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97       LOG_AUTHPRIV   The same as LOG_AUTH , but logged  to  a  file  readable
98                      only by selected individuals.
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100       LOG_CRON       The clock daemon.
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102       LOG_DAEMON     System daemons, such as routed(8), that are not provided
103                      for explicitly by other facilities.
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105       LOG_KERN       Messages generated by the kernel.  These cannot be  gen‐
106                      erated by any user processes.
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108       LOG_LPR        The   line  printer  spooling  system:  lpr(1),  lpc(8),
109                      lpd(8), etc.
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111       LOG_MAIL       The mail system.
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113       LOG_NEWS       The network news system.
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115       LOG_SYSLOG     Messages generated internally by syslogd(8).
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117       LOG_USER       Messages generated by random user  processes.   This  is
118                      the default facility identifier if none is specified.
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120       LOG_UUCP       The uucp system.
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122       LOG_LOCAL0     Reserved   for  local  use.   Similarly  for  LOG_LOCAL1
123                      through LOG_LOCAL7.
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125       The closelog function can be used to close the log file.
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127       The setlogmask function sets the  log  priority  mask  to  maskpri  and
128       returns  the previous mask.  Calls to syslog with a priority not set in
129       maskpri are rejected.  The mask for an individual priority pri is  cal‐
130       culated  by the macro LOG_MASK(pri).  The mask for all priorities up to
131       and including toppri is  given  by  the  macro  LOG_UPTO(toppri).   The
132       default allows all priorities to be logged.
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RETURN VALUES

135       The  routines  closelog(),  openlog(), syslog() and vsyslog() return no
136       value.
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138       The routine setlogmask() always returns the previous log mask level.
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EXAMPLES

141               syslog(LOG_ALERT, "who: internal error 23");
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143               openlog("ftpd",       LOG_PID,       LOG_DAEMON);       setlog‐
144               mask(LOG_UPTO(LOG_ERR)); syslog(LOG_INFO, "Connection from host
145               %d", CallingHost);
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147               syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m");
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BUGS

153       Under 2.11BSD the logfile /usr/adm/messages is used if a non networking
154       kernel has been booted.  That file must be publically writeable in this
155       case.
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HISTORY

158       These functions appeared in 4.2BSD.
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1624.2 Berkeley Distribution        April 1, 1995                       SYSLOG(3)