1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)syslog.3 8.1 (Berkeley) 6/4/93 33.\" 34.Dd June 4, 1993 35.Dt SYSLOG 3 36.Os BSD 4.2 37.Sh NAME 38.Nm syslog , 39.Nm vsyslog , 40.Nm openlog , 41.Nm closelog , 42.Nm setlogmask 43.Nd control system log 44.Sh SYNOPSIS 45.Fd #include <syslog.h> 46.Fd #include <varargs.h> 47.Ft void 48.Fn syslog "int priority" "const char *message" "..." 49.Ft void 50.Fn vsyslog "int priority" "const char *message" "va_list args" 51.Ft void 52.Fn openlog "const char *ident" "int logopt" "int facility" 53.Ft void 54.Fn closelog void 55.Ft int 56.Fn setlogmask "int maskpri" 57.Sh DESCRIPTION 58The 59.Fn syslog 60function 61writes 62.Fa message 63to the system message logger. 64The message is then written to the system console, log files, 65logged-in users, or forwarded to other machines as appropriate. (See 66.Xr syslogd 8 . ) 67.Pp 68The message is identical to a 69.Xr printf 3 70format string, except that 71.Ql %m 72is replaced by the current error 73message. (As denoted by the global variable 74.Va errno ; 75see 76.Xr strerror 3 . ) 77A trailing newline is added if none is present. 78.Pp 79The 80.Fn vsyslog 81function 82is an alternate form in which the arguments have already been captured 83using the variable-length argument facilities of 84.Xr varargs 3 . 85.Pp 86The message is tagged with 87.Fa priority . 88Priorities are encoded as a 89.Fa facility 90and a 91.Em level . 92The facility describes the part of the system 93generating the message. 94The level is selected from the following 95.Em ordered 96(high to low) list: 97.Bl -tag -width LOG_AUTHPRIV 98.It Dv LOG_EMERG 99A panic condition. 100This is normally broadcast to all users. 101.It Dv LOG_ALERT 102A condition that should be corrected immediately, such as a corrupted 103system database. 104.It Dv LOG_CRIT 105Critical conditions, e.g., hard device errors. 106.It Dv LOG_ERR 107Errors. 108.It Dv LOG_WARNING 109Warning messages. 110.It Dv LOG_NOTICE 111Conditions that are not error conditions, 112but should possibly be handled specially. 113.It Dv LOG_INFO 114Informational messages. 115.It Dv LOG_DEBUG 116Messages that contain information 117normally of use only when debugging a program. 118.El 119.Pp 120The 121.Fn openlog 122function 123provides for more specialized processing of the messages sent 124by 125.Fn syslog 126and 127.Fn vsyslog . 128The parameter 129.Fa ident 130is a string that will be prepended to every message. 131The 132.Fa logopt 133argument 134is a bit field specifying logging options, which is formed by 135.Tn OR Ns 'ing 136one or more of the following values: 137.Bl -tag -width LOG_AUTHPRIV 138.It Dv LOG_CONS 139If 140.Fn syslog 141cannot pass the message to 142.Xr syslogd 143it will attempt to write the message to the console 144.Pq Dq Pa /dev/console. 145.It Dv LOG_NDELAY 146Open the connection to 147.Xr syslogd 148immediately. 149Normally the open is delayed until the first message is logged. 150Useful for programs that need to manage the order in which file 151descriptors are allocated. 152.It Dv LOG_PERROR 153Write the message to standard error output as well to the system log. 154.It Dv LOG_PID 155Log the process id with each message: useful for identifying 156instantiations of daemons. 157.El 158.Pp 159The 160.Fa facility 161parameter encodes a default facility to be assigned to all messages 162that do not have an explicit facility encoded: 163.Bl -tag -width LOG_AUTHPRIV 164.It Dv LOG_AUTH 165The authorization system: 166.Xr login 1 , 167.Xr su 1 , 168.Xr getty 8 , 169etc. 170.It Dv LOG_AUTHPRIV 171The same as 172.Dv LOG_AUTH , 173but logged to a file readable only by 174selected individuals. 175.It Dv LOG_CRON 176The clock daemon. 177.It Dv LOG_DAEMON 178System daemons, such as 179.Xr routed 8 , 180that are not provided for explicitly by other facilities. 181.It Dv LOG_KERN 182Messages generated by the kernel. 183These cannot be generated by any user processes. 184.It Dv LOG_LPR 185The line printer spooling system: 186.Xr lpr 1 , 187.Xr lpc 8 , 188.Xr lpd 8 , 189etc. 190.It Dv LOG_MAIL 191The mail system. 192.It Dv LOG_NEWS 193The network news system. 194.It Dv LOG_SYSLOG 195Messages generated internally by 196.Xr syslogd 8 . 197.It Dv LOG_USER 198Messages generated by random user processes. 199This is the default facility identifier if none is specified. 200.It Dv LOG_UUCP 201The uucp system. 202.It Dv LOG_LOCAL0 203Reserved for local use. 204Similarly for 205.Dv LOG_LOCAL1 206through 207.Dv LOG_LOCAL7 . 208.El 209.Pp 210The 211.Fn closelog 212function 213can be used to close the log file. 214.Pp 215The 216.Fn setlogmask 217function 218sets the log priority mask to 219.Fa maskpri 220and returns the previous mask. 221Calls to 222.Fn syslog 223with a priority not set in 224.Fa maskpri 225are rejected. 226The mask for an individual priority 227.Fa pri 228is calculated by the macro 229.Fn LOG_MASK pri ; 230the mask for all priorities up to and including 231.Fa toppri 232is given by the macro 233.Fn LOG_UPTO toppri ; . 234The default allows all priorities to be logged. 235.Sh RETURN VALUES 236The routines 237.Fn closelog , 238.Fn openlog , 239.Fn syslog 240and 241.Fn vsyslog 242return no value. 243.Pp 244The routine 245.Fn setlogmask 246always returns the previous log mask level. 247.Sh EXAMPLES 248.Bd -literal -offset indent -compact 249syslog(LOG_ALERT, "who: internal error 23"); 250 251openlog("ftpd", LOG_PID, LOG_DAEMON); 252setlogmask(LOG_UPTO(LOG_ERR)); 253syslog(LOG_INFO, "Connection from host %d", CallingHost); 254 255syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m"); 256.Ed 257.Sh SEE ALSO 258.Xr logger 1 , 259.Xr syslogd 8 260.Sh HISTORY 261These 262functions appeared in 263.Bx 4.2 . 264