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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)

COMMENTS