usr/man/man3/syslog.3

.TH SYSLOG 3 "14 November 1982"
.\"     @(#)syslog.3    1.2             11/14/82
.SH NAME
syslog, openlog, closelog \- control system log
.SH SYNOPSIS
.B "#include <syslog.h>
.PP
.B "openlog(ident, logstat)
.br
.B "char *ident;
.PP
.B "syslog(priority, message, parameters ... )
.br
.B "char *message;
.PP
.B "closelog()
.SH DESCRIPTION
.I Syslog
arranges to write the
.I message
onto the system log maintained by
.IR syslog (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 syslog (8)
and output to the system console or files as appropriate.
.PP
If special processing is needed,
.I openlog
can be called to initialize the log file.
Parameters are
.I ident
which is prepended to every message, and
.I logstat
which is a bit field indicating special status; current values are:
.IP LOG_PID \w'LOG_PID'u+3
log the process id with each message:
useful for identifying instantiations of daemons.
.LP
.I Openlog
returns zero on success.
If it cannot open the file
.I /dev/log,
it writes on
.I /dev/console
instead and returns \-1.
.PP
.I Closelog
can be used to close the log file.
.SH EXAMPLES
.nf
syslog(LOG_SALERT, "who: internal error 23");

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