SYSLOG(3)

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
    system daemons without separate facility value

LOG_FTP
    ftp daemon

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)