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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 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 $ 30.\" 31.Dd June 4, 1993 32.Dt SYSLOG 3 33.Os 34.Sh NAME 35.Nm syslog , 36.Nm vsyslog , 37.Nm openlog , 38.Nm closelog , 39.Nm setlogmask 40.Nd control system log 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In syslog.h 45.In stdarg.h 46.Ft void 47.Fn syslog "int priority" "const char *message" "..." 48.Ft void 49.Fn vsyslog "int priority" "const char *message" "va_list args" 50.Ft void 51.Fn openlog "const char *ident" "int logopt" "int facility" 52.Ft void 53.Fn closelog void 54.Ft int 55.Fn setlogmask "int maskpri" 56.Sh DESCRIPTION 57The 58.Fn syslog 59function 60writes 61.Fa message 62to the system message logger. 63The message is then written to the system console, log files, 64logged-in users, or forwarded to other machines as appropriate. 65(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. 74(As denoted by the global variable 75.Va errno ; 76see 77.Xr strerror 3 . ) 78A trailing newline is added if none is present. 79.Pp 80The 81.Fn vsyslog 82function 83is an alternate form in which the arguments have already been captured 84using the variable-length argument facilities of 85.Xr stdarg 3 . 86.Pp 87The message is tagged with 88.Fa priority . 89Priorities are encoded as a 90.Fa facility 91and a 92.Em level . 93The facility describes the part of the system 94generating the message. 95The level is selected from the following 96.Em ordered 97(high to low) list: 98.Bl -tag -width ".Dv LOG_AUTHPRIV" 99.It Dv LOG_EMERG 100A panic condition. 101This is normally broadcast to all users. 102.It Dv LOG_ALERT 103A condition that should be corrected immediately, such as a corrupted 104system database. 105.It Dv LOG_CRIT 106Critical conditions, e.g., hard device errors. 107.It Dv LOG_ERR 108Errors. 109.It Dv LOG_WARNING 110Warning messages. 111.It Dv LOG_NOTICE 112Conditions that are not error conditions, 113but should possibly be handled specially. 114.It Dv LOG_INFO 115Informational messages. 116.It Dv LOG_DEBUG 117Messages that contain information 118normally of use only when debugging a program. 119.El 120.Pp 121The 122.Fn openlog 123function 124provides for more specialized processing of the messages sent 125by 126.Fn syslog 127and 128.Fn vsyslog . 129The parameter 130.Fa ident 131is a string that will be prepended to every message. 132The 133.Fa logopt 134argument 135is a bit field specifying logging options, which is formed by 136.Tn OR Ns 'ing 137one or more of the following values: 138.Bl -tag -width ".Dv LOG_AUTHPRIV" 139.It Dv LOG_CONS 140If 141.Fn syslog 142cannot pass the message to 143.Xr syslogd 8 144it will attempt to write the message to the console 145.Pq Dq Pa /dev/console . 146.It Dv LOG_NDELAY 147Open the connection to 148.Xr syslogd 8 149immediately. 150Normally the open is delayed until the first message is logged. 151Useful for programs that need to manage the order in which file 152descriptors are allocated. 153.It Dv LOG_PERROR 154Write the message to standard error output as well to the system log. 155.It Dv LOG_PID 156Log the process id with each message: useful for identifying 157instantiations of daemons. 158.El 159.Pp 160The 161.Fa facility 162parameter encodes a default facility to be assigned to all messages 163that do not have an explicit facility encoded: 164.Bl -tag -width ".Dv LOG_AUTHPRIV" 165.It Dv LOG_AUTH 166The authorization system: 167.Xr login 1 , 168.Xr su 1 , 169.Xr getty 8 , 170etc. 171.It Dv LOG_AUTHPRIV 172The same as 173.Dv LOG_AUTH , 174but logged to a file readable only by 175selected individuals. 176.It Dv LOG_CONSOLE 177Messages written to 178.Pa /dev/console 179by the kernel console output driver. 180.It Dv LOG_CRON 181The cron daemon: 182.Xr cron 8 . 183.It Dv LOG_DAEMON 184System daemons, such as 185.Xr routed 8 , 186that are not provided for explicitly by other facilities. 187.It Dv LOG_FTP 188The file transfer protocol daemons: 189.Xr ftpd 8 , 190.Xr tftpd 8 . 191.It Dv LOG_KERN 192Messages generated by the kernel. 193These cannot be generated by any user processes. 194.It Dv LOG_LPR 195The line printer spooling system: 196.Xr lpr 1 , 197.Xr lpc 8 , 198.Xr lpd 8 , 199etc. 200.It Dv LOG_MAIL 201The mail system. 202.It Dv LOG_NEWS 203The network news system. 204.It Dv LOG_SECURITY 205Security subsystems, such as 206.Xr ipfw 4 . 207.It Dv LOG_SYSLOG 208Messages generated internally by 209.Xr syslogd 8 . 210.It Dv LOG_USER 211Messages generated by random user processes. 212This is the default facility identifier if none is specified. 213.It Dv LOG_UUCP 214The uucp system. 215.It Dv LOG_LOCAL0 216Reserved for local use. 217Similarly for 218.Dv LOG_LOCAL1 219through 220.Dv LOG_LOCAL7 . 221.El 222.Pp 223The 224.Fn closelog 225function 226can be used to close the log file. 227.Pp 228The 229.Fn setlogmask 230function 231sets the log priority mask to 232.Fa maskpri 233and returns the previous mask. 234Calls to 235.Fn syslog 236with a priority not set in 237.Fa maskpri 238are rejected. 239The mask for an individual priority 240.Fa pri 241is calculated by the macro 242.Fn LOG_MASK pri ; 243the mask for all priorities up to and including 244.Fa toppri 245is given by the macro 246.Fn LOG_UPTO toppri ; . 247The default allows all priorities to be logged. 248.Sh RETURN VALUES 249The routines 250.Fn closelog , 251.Fn openlog , 252.Fn syslog 253and 254.Fn vsyslog 255return no value. 256.Pp 257The routine 258.Fn setlogmask 259always returns the previous log mask level. 260.Sh EXAMPLES 261.Bd -literal -offset indent -compact 262syslog(LOG_ALERT, "who: internal error 23"); 263 264openlog("ftpd", LOG_PID | LOG_NDELAY, LOG_FTP); 265 266setlogmask(LOG_UPTO(LOG_ERR)); 267 268syslog(LOG_INFO, "Connection from host %d", CallingHost); 269 270syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m"); 271.Ed 272.Sh SEE ALSO 273.Xr logger 1 , 274.Xr syslogd 8 275.Sh HISTORY 276These 277functions appeared in 278.Bx 4.2 . 279