syslog(3)
NAME
syslog, openlog, closelog − control system log
SYNTAX
#include <syslog.h>
openlog(ident, logstat)
char *ident;
syslog(priority, message, parameters ... )
char *message;
closelog()
DESCRIPTION
The syslog subroutine arranges to write the message onto the system log maintained by syslog(8). The message is tagged with priority. The message looks like a printf(3s) string except that %m is replaced by the current error message (collected from errno). A trailing newline is added if needed. This message will be read by syslog(8) and output to the system console or files as appropriate.
If special processing is needed, openlog can be called to initialize the log file. Parameters are ident which is prepended to every message, and logstat which is a bit field indicating special status; current values are:
LOG_PIDlog the process id with each message: useful for identifying instantiations of daemons.
The openlog subroutine returns zero on success. If it cannot establish a network connection with the syslog daemon, it writes on /dev/console instead and returns −1.
The closelog subroutine can be used to close the log file.
EXAMPLES
syslog(LOG_SALERT, "who: internal error 23");
openlog("serverftp", LOG_PID);
syslog(LOG_INFO, "Connection from host %d", CallingHost);