NAME¶
closelog, openlog, syslog - send messages to the system logger
SYNOPSIS¶
#include <syslog.h>
void openlog( char *ident, int option, int
facility)
void syslog( int priority, char *format, ...)
void closelog( void )
DESCRIPTION¶
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
syslogd(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.
PARAMETERS¶
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
- write directly to system console if there is an error while sending to
system logger
- LOG_NDELAY
- open the connection immediately (normally, the connection is opened when
the first message is logged)
- LOG_PERROR
- print to stderr as well
- LOG_PID
- 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
- security/authorization messages (DEPRECATED Use LOG_AUTHPRIV
instead)
- LOG_AUTHPRIV
- security/authorization messages (private)
- LOG_CRON
- clock daemon (cron and at)
- LOG_DAEMON
- other system daemons
- LOG_KERN
- kernel messages
- LOG_LOCAL0 through LOG_LOCAL7
- reserved for local use
- LOG_LPR
- line printer subsystem
- LOG_MAIL
- mail subsystem
- LOG_NEWS
- USENET news subsystem
- LOG_SYSLOG
- messages generated internally by syslogd
- LOG_USER(default)
- generic user-level messages
- LOG_UUCP
- UUCP subsystem
level¶
This determines the importance of the message. The levels are, in order of
decreasing importance:
- LOG_EMERG
- system is unusable
- LOG_ALERT
- action must be taken immediately
- LOG_CRIT
- critical conditions
- LOG_ERR
- error conditions
- LOG_WARNING
- warning conditions
- LOG_NOTICE
- normal, but significant, condition
- LOG_INFO
- informational message
- LOG_DEBUG
- debug-level message
HISTORY¶
A
syslog function call appeared in BSD 4.2.
SEE ALSO¶
logger(1),
syslog.conf(5),
syslogd(8)