syslog.3

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)syslog.3	8.2	1/28/91
.TH syslog 3
.SH Name
syslog, openlog, closelog \- control system log
.SH Syntax
.B "#include <syslog.h>
.PP
.B "openlog(ident, logstat)
.br
.B "char *ident;
.PP
.B "void syslog(priority, message, parameters ... )
.br
.B "char *message;
.PP
.B "void closelog()
.SH Description
.NXR "syslog subroutine"
.NXR "openlog subroutine"
.NXR "closelog subroutine"
.NXR "system log" "controlling"
The
.PN syslog
subroutine arranges to write the message onto the system log maintained by
.MS syslog 8 .
The message is tagged with priority and it looks like a
.MS printf 3s
string except that 
.B %m
is replaced by the current error message (collected from
.PN errno ).
A trailing new line is added if needed.
This message is read by
.MS syslog 8
and output to the system console or files as appropriate.
The maximum number of parameters is 5.
.PP
If special processing is needed,
.PN 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  9
log the process id with each message;
useful for identifying daemons.
.PP
The
.PN openlog
returns zero on success.
If it cannot open the file 
.PN /dev/log ,
it writes on 
.PN /dev/console
instead and returns \-1.
.PP
The
.PN closelog
can be used to close the log file.
.SH Examples
.EX 
syslog(LOG_SALERT, "who: internal error 23");

openlog("serverftp", LOG_PID);
syslog(LOG_INFO, "Connection from host %d", CallingHost);
.EE
.SH See Also
syslog(8)