closelog, openlog, syslog - send messages to the system logger
#include <syslog.h>
void openlog( char *ident, int option, int facility)
void syslog( int priority, char *format, ...)
void closelog( void )
closelog() closes the descriptor being used to write to the system logger.
The use of closelog() is optional.
openlog() opens a connection to the system logger for a program. The
string pointed to by ident is added to each message, and is typically
set to the program name. Values for option and facility are given in
the next section. The use of openlog() is optional; It will automatically
be called by syslog() if necessary, in which case ident will
default to NULL.
syslog() generates a log message, which will be distributed by sys-
logd(8). priority is a combination of the facility and the level, values
for which are given in the next section. The remaining arguments
are a format, as in printf(3) and any arguments required by the format,
except that the two character %m will be replaced by the error message
string (strerror) corresponding to the present value of errno.
This section lists the parameters used to set the values of option,
facility, and priority.
option
The option argument to openlog() is an OR of any of these:
LOG_CONS [Toc] [Back]
write directly to system console if there is an error while
sending to system logger
LOG_NDELAY [Toc] [Back]
open the connection immediately (normally, the connection is
opened when the first message is logged)
LOG_PERROR [Toc] [Back]
print to stderr as well
LOG_PID [Toc] [Back]
include PID with each message
facility
The facility argument is used to specify what type of program is logging
the message. This lets the configuration file specify that messages
from different facilities will be handled differently.
LOG_AUTH [Toc] [Back]
security/authorization messages (DEPRECATED Use LOG_AUTHPRIV
instead)
LOG_AUTHPRIV [Toc] [Back]
security/authorization messages (private)
LOG_CRON [Toc] [Back]
clock daemon (cron and at)
LOG_DAEMON [Toc] [Back]
system daemons without separate facility value
LOG_FTP [Toc] [Back]
ftp daemon
LOG_KERN [Toc] [Back]
kernel messages
LOG_LOCAL0 through LOG_LOCAL7
reserved for local use
LOG_LPR [Toc] [Back]
line printer subsystem
LOG_MAIL [Toc] [Back]
mail subsystem
LOG_NEWS [Toc] [Back]
USENET news subsystem
LOG_SYSLOG [Toc] [Back]
messages generated internally by syslogd
LOG_USER(default)
generic user-level messages
LOG_UUCP [Toc] [Back]
UUCP subsystem
level
This determines the importance of the message. The levels are, in
order of decreasing importance:
LOG_EMERG [Toc] [Back]
system is unusable
LOG_ALERT [Toc] [Back]
action must be taken immediately
LOG_CRIT [Toc] [Back]
critical conditions
LOG_ERR [Toc] [Back]
error conditions
LOG_WARNING [Toc] [Back]
warning conditions
LOG_NOTICE [Toc] [Back]
normal, but significant, condition
LOG_INFO [Toc] [Back]
informational message
LOG_DEBUG [Toc] [Back]
debug-level message
A syslog function call appeared in BSD 4.2.
logger(1), syslog.conf(5), syslogd(8)
Linux 1999-12-19 SYSLOG(3)
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