This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
517 lines
13 KiB
Groff
517 lines
13 KiB
Groff
.\" $NetBSD: syslog.3,v 1.28 2010/05/13 18:04:58 jruoho Exp $
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.\" $OpenBSD: syslog.3,v 1.25 2005/07/22 03:16:58 jaredy Exp $
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.\"
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.\" Copyright (c) 1985, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)syslog.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd May 3, 2010
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.Dt SYSLOG 3
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.Os
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.Sh NAME
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.Nm syslog ,
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.Nm syslog_r ,
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.Nm vsyslog ,
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.Nm vsyslog_r ,
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.Nm syslogp ,
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.Nm syslogp_r ,
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.Nm vsyslogp ,
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.Nm vsyslogp_r ,
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.Nm openlog ,
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.Nm openlog_r ,
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.Nm closelog ,
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.Nm closelog_r ,
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.Nm setlogmask ,
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.Nm setlogmask_r
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.Nd control system log
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In syslog.h
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.Ft void
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.Fn syslog "int priority" "const char *message" "..."
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.Ft void
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.Fn syslog_r "int priority" "struct syslog_data *data" "const char *message" "..."
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.Ft void
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.Fn syslogp "int priority" "const char *msgid" "const char *sdfmt" "const char *message" "..."
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.Ft void
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.Fn syslogp_r "int priority" "struct syslog_data *data" "const char *msgid" "const char *sdfmt" "const char *message" "..."
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.\" .Ft void
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.\" .Fn syslog_ss "int priority" "struct syslog_data *data" "const char *message" "..."
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.Ft void
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.Fn openlog "const char *ident" "int logopt" "int facility"
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.Ft void
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.Fn openlog_r "const char *ident" "int logopt" "int facility" "struct syslog_data *data"
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.Ft void
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.Fn closelog void
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.Ft void
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.Fn closelog_r "struct syslog_data *data"
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.Ft int
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.Fn setlogmask "int maskpri"
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.Ft int
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.Fn setlogmask_r "int maskpri" "struct syslog_data *data"
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.In stdarg.h
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.Ft void
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.Fn vsyslog "int priority" "const char *message" "va_list args"
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.Ft void
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.Fn vsyslog_r "int priority" "struct syslog_data *data" "const char *message" "va_list args"
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.Ft void
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.Fn vsyslogp "int priority" "const char *msgid" "const char *sdfmt" "const char *message" "va_list args"
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.Ft void
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.Fn vsyslogp_r "int priority" "struct syslog_data *data" "const char *msgid" "const char *sdfmt" "const char *message" "va_list args"
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.\" .Ft void
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.\" .Fn vsyslog_ss "int priority" "struct syslog_data *data" "const char *message" "va_list args"
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.Sh DESCRIPTION
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The
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.Fn syslog
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function
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writes
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.Fa message
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to the system message logger.
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The message is then written to the system console, log files,
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logged-in users, or forwarded to other machines as appropriate (see
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.Xr syslogd 8 ) .
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.Pp
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The message is identical to a
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.Xr printf 3
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format string, except that
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.Ql %m
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is replaced by the current error
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message.
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(As denoted by the global variable
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.Va errno ;
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see
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.Xr strerror 3 . )
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A trailing newline is added if none is present.
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.\" shouldn't the newline statement be removed?
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.\" when logging through a socket a newline is
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.\" not added nor is it required. -- ms
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.Pp
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The
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.Fn syslog_r
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function is a multithread-safe version of the
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.Fn syslog
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function.
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It takes a pointer to a
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.Fa syslog_data
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structure which is used to store
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information.
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This parameter must be initialized before
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.Fn syslog_r
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is called.
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The
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.Dv SYSLOG_DATA_INIT
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constant is used for this purpose.
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The
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.Fa syslog_data
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structure and the
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.Dv SYSLOG_DATA_INIT
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constant are defined as:
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.Bd -literal -offset indent
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struct syslog_data {
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int log_file;
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int connected;
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int opened;
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int log_stat;
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const char *log_tag;
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int log_fac;
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int log_mask;
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};
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#define SYSLOG_DATA_INIT { \e
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.log_file = -1, \e
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.log_fac = LOG_USER, \e
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.log_mask = 0xff, \e
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}
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.Ed
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.Pp
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The structure is composed of the following elements:
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.Bl -tag -width connected -offset indent
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.It Va log_file
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contains the file descriptor of the file where the message is logged
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.It Va connected
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indicates if connect has been done
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.It Va opened
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indicates if
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.Fn openlog_r
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has been called
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.It Va log_stat
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status bits, set by
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.Fn openlog_r
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.It Va log_tag
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string to tag the entry with
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.It Va log_fac
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facility code
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.It Va log_mask
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mask of priorities to be logged
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.El
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.\" .Pp
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.\" The
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.\" .Fn syslog_ss
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.\" is the async-signal-safe version of
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.\" .Fn syslog_r
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.\" and is also multithread-safe.
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.\" It has the following limitations:
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.\" .Bl -enum -offset indent
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.\" .It
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.\" The format string cannot contain multi-byte character sequences.
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.\" .It
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.\" Floating point formats are not supported and print
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.\" .Dq UNK .
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.\" .It
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.\" The time of the event is not sent to
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.\" .Xr syslogd 8 .
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.\" .It
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.\" The error string in the %m format is not printed symbolically but as
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.\" .Dq Error %d .
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.\" .El
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.\" .Pp
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.\" For more information about async-signal-safe functions and signal handlers, see
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.\" .Xr signal 7 .
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.Pp
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The
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.Fn vsyslog
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function
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is an alternative form in which the arguments have already been captured
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using the variable-length argument facilities of
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.Xr varargs 3 .
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.Pp
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The
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.Fn syslogp
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variants take additional arguments which correspond to new fields in the
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syslog-protocol message format.
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All three arguments are evaluated as
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.Xr printf 3
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format strings and any of them can be
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.Dv NULL .
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This enables applications to use message IDs, structured data, and UTF-8 encoded
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content in messages.
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.Pp
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The message is tagged with
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.Fa priority .
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Priorities are encoded as a
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.Fa facility
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and a
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.Em level .
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The facility describes the part of the system
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generating the message.
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The level is selected from the following
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.Em ordered
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(high to low) list:
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.Bl -tag -width LOG_AUTHPRIV
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.It Dv LOG_EMERG
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A panic condition.
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This is normally broadcast to all users.
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.It Dv LOG_ALERT
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A condition that should be corrected immediately, such as a corrupted
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system database.
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.It Dv LOG_CRIT
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Critical conditions, e.g., hard device errors.
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.It Dv LOG_ERR
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Errors.
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.It Dv LOG_WARNING
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Warning messages.
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.It Dv LOG_NOTICE
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Conditions that are not error conditions,
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but should possibly be handled specially.
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.It Dv LOG_INFO
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Informational messages.
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.It Dv LOG_DEBUG
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Messages that contain information
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normally of use only when debugging a program.
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.El
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.Pp
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The
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.Fn vsyslog_r
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is used the same way as
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.Fn vsyslog
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except that it takes an additional pointer to a
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.Fa syslog_data
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structure.
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It is a multithread-safe version of the
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.Fn vsyslog
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function described above.
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.\" The
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.\" .Fn vsyslog_ss
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.\" is the async-signal-safe version of
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.\" .Fn vsyslog_r ,
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.\" is also multithread-safe, and has the same limitations as
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.\" .Fn syslog_ss .
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.Pp
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The
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.Fn openlog
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function
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provides for more specialized processing of the messages sent
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by
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.Fn syslog
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and
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.Fn vsyslog .
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The parameter
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.Fa ident
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is a string that will be prepended to every message.
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The
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.Fa logopt
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argument
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is a bit field specifying logging options, which is formed by
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.Tn OR Ns 'ing
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one or more of the following values:
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.Bl -tag -width LOG_AUTHPRIV
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.It Dv LOG_CONS
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If
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.Fn syslog
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cannot pass the message to
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.Xr syslogd 8
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it will attempt to write the message to the console
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.Pq Dq Pa /dev/console .
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.It Dv LOG_NDELAY
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Open the connection to
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.Xr syslogd 8
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immediately.
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Normally the open is delayed until the first message is logged.
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Useful for programs that need to manage the order in which file
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descriptors are allocated.
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.It Dv LOG_PERROR
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Write the message to standard error output as well to the system log.
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.It Dv LOG_PID
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Log the process id with each message: useful for identifying
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instantiations of daemons.
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(This PID is placed within brackets
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between the ident and the message.)
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.El
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.Pp
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The
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.Fa facility
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parameter encodes a default facility to be assigned to all messages
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that do not have an explicit facility encoded:
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.Bl -tag -width LOG_AUTHPRIV
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.It Dv LOG_AUTH
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The authorization system:
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.Xr login 1 ,
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.Xr su 1 ,
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.Xr getty 8 ,
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etc.
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.It Dv LOG_AUTHPRIV
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The same as
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.Dv LOG_AUTH ,
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but logged to a file readable only by
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selected individuals.
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.It Dv LOG_CRON
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The cron daemon:
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.Xr cron 8 .
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.It Dv LOG_DAEMON
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System daemons, such as
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.Xr routed 8 ,
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that are not provided for explicitly by other facilities.
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.It Dv LOG_FTP
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The file transfer protocol daemon:
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.Xr ftpd 8 .
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.It Dv LOG_KERN
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Messages generated by the kernel.
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These cannot be generated by any user processes.
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.It Dv LOG_LPR
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The line printer spooling system:
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.Xr lpr 1 ,
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.Xr lpc 8 ,
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.Xr lpd 8 ,
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etc.
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.It Dv LOG_MAIL
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The mail system.
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.It Dv LOG_NEWS
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The network news system.
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.It Dv LOG_SYSLOG
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Messages generated internally by
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.Xr syslogd 8 .
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.It Dv LOG_USER
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Messages generated by random user processes.
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This is the default facility identifier if none is specified.
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.It Dv LOG_UUCP
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The uucp system.
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.It Dv LOG_LOCAL0
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Reserved for local use.
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Similarly for
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.Dv LOG_LOCAL1
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through
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.Dv LOG_LOCAL7 .
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.El
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.Pp
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The
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.Fn openlog_r
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function is the multithread-safe version of the
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.Fn openlog
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function.
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It takes an additional pointer to a
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.Fa syslog_data
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structure.
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This function must be used in conjunction with the other
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multithread-safe functions.
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.Pp
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The
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.Fn closelog
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function
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can be used to close the log file.
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.Pp
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The
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.Fn closelog_r
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does the same thing as
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.Xr closelog 3
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but in a multithread-safe way and takes an additional
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pointer to a
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.Fa syslog_data
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structure.
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.Pp
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The
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.Fn setlogmask
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function
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sets the log priority mask to
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.Fa maskpri
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and returns the previous mask.
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Calls to
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.Fn syslog
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with a priority not set in
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.Fa maskpri
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are rejected.
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The mask for an individual priority
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.Fa pri
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is calculated by the macro
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.Fn LOG_MASK pri ;
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the mask for all priorities up to and including
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.Fa toppri
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is given by the macro
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.Fn LOG_UPTO toppri .
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The default allows all priorities to be logged.
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.Pp
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The
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.Fn setlogmask_r
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function is the multithread-safe version of
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.Fn setlogmask .
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It takes an additional pointer to a
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.Fa syslog_data
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structure.
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.Sh RETURN VALUES
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The routines
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.Fn closelog ,
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.Fn closelog_r ,
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.Fn openlog ,
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.Fn openlog_r ,
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.Fn syslog ,
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.Fn syslog_r ,
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.Fn vsyslog ,
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.Fn vsyslog_r ,
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.Fn syslogp ,
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.Fn syslogp_r ,
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.Fn vsyslogp ,
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and
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.Fn vsyslogp_r
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return no value.
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.Pp
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The routines
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.Fn setlogmask
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and
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.Fn setlogmask_r
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always return the previous log mask level.
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.Sh EXAMPLES
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.Bd -literal -offset indent -compact
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syslog(LOG_ALERT, "who: internal error 23");
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openlog("ftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
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setlogmask(LOG_UPTO(LOG_ERR));
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syslog(LOG_INFO, "Connection from host %d", CallingHost);
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syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m");
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syslogp(LOG_INFO|LOG_LOCAL2, NULL, NULL, "foobar error: %m");
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syslogp(LOG_INFO, "ID%d", "[meta language=\e"en-US\e"]",
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"event: %s", 42, EventDescription);
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.Ed
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.Pp
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For the multithread-safe functions:
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.Bd -literal -offset indent
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struct syslog_data sdata = SYSLOG_DATA_INIT;
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syslog_r(LOG_INFO|LOG_LOCAL2, \*[Am]sdata, "foobar error: %m");
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.Ed
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.Sh SEE ALSO
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.Xr logger 1 ,
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.Xr syslogd 8
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.Rs
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.%R RFC
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.%N 3164
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.%D August 2001
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.%T The BSD syslog Protocol
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.Re
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.Rs
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.%R Internet-Draft
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.%N draft-ietf-syslog-protocol-23
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.%D September 2007
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.%T The syslog Protocol
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.Re
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.Sh HISTORY
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These non-multithread-safe functions appeared in
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.Bx 4.2 .
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The multithread-safe functions appeared in
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.Ox 3.1
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and then in
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.Nx 4.0 .
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The async-signal-safe functions appeared in
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.Nx 4.0 .
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The syslog-protocol functions appeared in
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.Nx 5.0 .
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.Sh CAVEATS
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|
It is important never to pass a string with user-supplied data as a
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format without using
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.Ql %s .
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An attacker can put format specifiers in the string to mangle your stack,
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leading to a possible security hole.
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This holds true even if you have built the string
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.Dq by hand
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using a function like
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.Fn snprintf ,
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as the resulting string may still contain user-supplied conversion specifiers
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for later interpolation by
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.Fn syslog .
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.Pp
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Always be sure to use the proper secure idiom:
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.Bd -literal -offset indent
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syslog(priority, "%s", string);
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.Ed
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.Pp
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With
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.Fn syslogp
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the caller is responsible to use the right formatting for the message fields.
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A
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.Fa msgid
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must only contain up to 32 ASCII characters.
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A
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.Fa sdfmt
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has strict rules for paranthesis and character quoting.
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If the
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.Fa msgfmt
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contains UTF-8 characters, then it has to start with a Byte Order Mark.
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