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.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt SYSLOG 3 37.Os BSD 4.2 38.Sh NAME 39.Nm syslog , 40.Nm vsyslog , 41.Nm openlog , 42.Nm closelog , 43.Nm setlogmask 44.Nd control system log 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.Fd #include <syslog.h> 49.Fd #include <varargs.h> 50.Ft void 51.Fn syslog "int priority" "const char *message" "..." 52.Ft void 53.Fn vsyslog "int priority" "const char *message" "va_list args" 54.Ft void 55.Fn openlog "const char *ident" "int logopt" "int facility" 56.Ft void 57.Fn closelog void 58.Ft int 59.Fn setlogmask "int maskpri" 60.Sh DESCRIPTION 61The 62.Fn syslog 63function 64writes 65.Fa message 66to the system message logger. 67The message is then written to the system console, log files, 68logged-in users, or forwarded to other machines as appropriate. 69(See 70.Xr syslogd 8 . ) 71.Pp 72The message is identical to a 73.Xr printf 3 74format string, except that 75.Ql %m 76is replaced by the current error 77message. 78(As denoted by the global variable 79.Va errno ; 80see 81.Xr strerror 3 . ) 82A trailing newline is added if none is present. 83.Pp 84The 85.Fn vsyslog 86function 87is an alternate form in which the arguments have already been captured 88using the variable-length argument facilities of 89.Xr varargs 3 . 90.Pp 91The message is tagged with 92.Fa priority . 93Priorities are encoded as a 94.Fa facility 95and a 96.Em level . 97The facility describes the part of the system 98generating the message. 99The level is selected from the following 100.Em ordered 101(high to low) list: 102.Bl -tag -width LOG_AUTHPRIV 103.It Dv LOG_EMERG 104A panic condition. 105This is normally broadcast to all users. 106.It Dv LOG_ALERT 107A condition that should be corrected immediately, such as a corrupted 108system database. 109.It Dv LOG_CRIT 110Critical conditions, e.g., hard device errors. 111.It Dv LOG_ERR 112Errors. 113.It Dv LOG_WARNING 114Warning messages. 115.It Dv LOG_NOTICE 116Conditions that are not error conditions, 117but should possibly be handled specially. 118.It Dv LOG_INFO 119Informational messages. 120.It Dv LOG_DEBUG 121Messages that contain information 122normally of use only when debugging a program. 123.El 124.Pp 125The 126.Fn openlog 127function 128provides for more specialized processing of the messages sent 129by 130.Fn syslog 131and 132.Fn vsyslog . 133The parameter 134.Fa ident 135is a string that will be prepended to every message. 136The 137.Fa logopt 138argument 139is a bit field specifying logging options, which is formed by 140.Tn OR Ns 'ing 141one or more of the following values: 142.Bl -tag -width LOG_AUTHPRIV 143.It Dv LOG_CONS 144If 145.Fn syslog 146cannot pass the message to 147.Xr syslogd 8 148it will attempt to write the message to the console 149.Pq Dq Pa /dev/console. 150.It Dv LOG_NDELAY 151Open the connection to 152.Xr syslogd 8 153immediately. 154Normally the open is delayed until the first message is logged. 155Useful for programs that need to manage the order in which file 156descriptors are allocated. 157.It Dv LOG_PERROR 158Write the message to standard error output as well to the system log. 159.It Dv LOG_PID 160Log the process id with each message: useful for identifying 161instantiations of daemons. 162.El 163.Pp 164The 165.Fa facility 166parameter encodes a default facility to be assigned to all messages 167that do not have an explicit facility encoded: 168.Bl -tag -width LOG_AUTHPRIV 169.It Dv LOG_AUTH 170The authorization system: 171.Xr login 1 , 172.Xr su 1 , 173.Xr getty 8 , 174etc. 175.It Dv LOG_AUTHPRIV 176The same as 177.Dv LOG_AUTH , 178but logged to a file readable only by 179selected individuals. 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.It Dv LOG_SYSLOG 207Messages generated internally by 208.Xr syslogd 8 . 209.It Dv LOG_USER 210Messages generated by random user processes. 211This is the default facility identifier if none is specified. 212.It Dv LOG_UUCP 213The uucp system. 214.Xr ipfw 4 . 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