I know it works, but ...

[unix-history] / usr / src / lib / libc / gen / syslog.3

.\" Copyright (c) 1983 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)syslog.3	6.1 (Berkeley) %G%
.\"
.TH SYSLOG 3 ""
.UC 5
.SH NAME
syslog, openlog, closelog, setlogmask \- control system log
.SH SYNOPSIS
.B "#include <syslog.h>
.PP
.B "openlog(ident, logopt, maskpri)
.br
.B "char *ident;
.PP
.B "syslog(priority, message, parameters ... )
.br
.B "char *message;
.PP
.B "closelog()
.PP
.B "setlogmask(maskpri)
.SH DESCRIPTION
.I Syslog
arranges to write
.I message
onto the system log maintained by
.IR syslogd (8).
The message is tagged with
.IR priority .
The message looks like a
.IR printf (3)
string except that
.B %m
is replaced by the current error message (collected from
.IR errno ).
A trailing newline is added if needed.
This message will be read by
.IR syslogd (8)
and written to the system console, log files, or forwarded to
.I syslogd
on another host as appropriate.
If
.I syslog
cannot pass the message to
.I syslogd
and the message is priority LOG_FAIL or higher,
it attempts to write the message on
.IR /dev/console.
.PP
If special processing is needed,
.I openlog
can be called to initialize the log file.
The parameter
.I ident
is a string that is prepended to every message.
.I Logopt
is a bit field indicating logging options.
Current values for
.I logopt
are:
.IP LOG_PID \w'LOG_ODELAY'u+3
log the process id with each message:
useful for identifying instantiations of daemons.
.IP LOG_CONS \w'LOG_ODELAY'u+3
Force writing error messages to the console if unable to send it to
.I syslogd.
This option is safe to use in daemon processes that have no controlling
terminal since
.I syslog
will fork before opening the console.
.IP LOG_ODELAY \w'LOG_ODELAY'u+3
Delay opening the connection to
.I syslogd
until the first error occurs. Useful for programs that need to manage the
order in which file descriptors are allocated.
.PP
The
.I maskpri
parameter is a mask for screening out low priority messages.
Calls to
.I syslog
with a priority whose corresponding bit in
.I maskpri
is not set are ignored.
The default allows all priorities to be logged.
.PP
.I Closelog
can be used to close the log file.
.PP
.I Setlogmask
sets the log priority mask to
.I maskpri
and returns the previous mask.
Priorities and masks of 0 are ignored.
.SH EXAMPLES
.nf
syslog(LOG_SALERT, "who: internal error 23");

openlog("serverftp", LOG_PID, 0);
syslog(LOG_INFO, "Connection from host %d", CallingHost);
.fi
.SH "SEE ALSO"
syslogd(8)