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28 .\" @(#)syslog.3 8.1 (Berkeley) 6/4/93
29 .\" $FreeBSD: src/lib/libc/gen/syslog.3,v 1.9.2.9 2001/12/14 18:33:51 ru Exp $
40 .Nd control system log
47 .Fn syslog "int priority" "const char *message" "..."
49 .Fn vsyslog "int priority" "const char *message" "va_list args"
51 .Fn openlog "const char *ident" "int logopt" "int facility"
55 .Fn setlogmask "int maskpri"
62 to the system message logger.
63 The message is then written to the system console, log files,
64 logged-in users, or forwarded to other machines as appropriate.
68 The message is identical to a
70 format string, except that
72 is replaced by the current error
74 (As denoted by the global variable
78 A trailing newline is added if none is present.
83 is an alternate form in which the arguments have already been captured
84 using the variable-length argument facilities of
87 The message is tagged with
89 Priorities are encoded as a
93 The facility describes the part of the system
94 generating the message.
95 The level is selected from the following
98 .Bl -tag -width ".Dv LOG_AUTHPRIV"
101 This is normally broadcast to all users.
103 A condition that should be corrected immediately, such as a corrupted
106 Critical conditions, e.g., hard device errors.
112 Conditions that are not error conditions,
113 but should possibly be handled specially.
115 Informational messages.
117 Messages that contain information
118 normally of use only when debugging a program.
124 provides for more specialized processing of the messages sent
131 is a string that will be prepended to every message.
135 is a bit field specifying logging options, which is formed by
137 one or more of the following values:
138 .Bl -tag -width ".Dv LOG_AUTHPRIV"
142 cannot pass the message to
144 it will attempt to write the message to the console
145 .Pq Dq Pa /dev/console .
147 Open the connection to
150 Normally the open is delayed until the first message is logged.
151 Useful for programs that need to manage the order in which file
152 descriptors are allocated.
154 Write the message to standard error output as well to the system log.
156 Log the process id with each message: useful for identifying
157 instantiations of daemons.
162 parameter encodes a default facility to be assigned to all messages
163 that do not have an explicit facility encoded:
164 .Bl -tag -width ".Dv LOG_AUTHPRIV"
166 The authorization system:
174 but logged to a file readable only by
175 selected individuals.
179 by the kernel console output driver.
184 System daemons, such as
186 that are not provided for explicitly by other facilities.
188 The file transfer protocol daemons:
192 Messages generated by the kernel.
193 These cannot be generated by any user processes.
195 The line printer spooling system:
203 The network news system.
205 Security subsystems, such as
208 Messages generated internally by
211 Messages generated by random user processes.
212 This is the default facility identifier if none is specified.
216 Reserved for local use.
226 can be used to close the log file.
231 sets the log priority mask to
233 and returns the previous mask.
236 with a priority not set in
239 The mask for an individual priority
241 is calculated by the macro
243 the mask for all priorities up to and including
245 is given by the macro
246 .Fn LOG_UPTO toppri ; .
247 The default allows all priorities to be logged.
259 always returns the previous log mask level.
261 .Bd -literal -offset indent -compact
262 syslog(LOG_ALERT, "who: internal error 23");
264 openlog("ftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
266 setlogmask(LOG_UPTO(LOG_ERR));
268 syslog(LOG_INFO, "Connection from host %d", CallingHost);
270 syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m");
277 functions appeared in