OSF

NAME

syslog, openlog, closelog, setlogmask − Controls the system log

LIBRARY

Standard C Library (libc.a)

SYNOPSIS

#include <syslog.h>
int openlog (
char ∗id,
int log_option,
int facility );
int syslog (
int priority,
char ∗message [, value... ] );
int closelog ( void );
int setlogmask(
int mask_priority );

PARAMETERS

idSpecifies a string that is attached to the beginning of every message. 

log_optionSpecifies logging options.  Values of the log_option parameter include:

Log the process ID with each message.
This option" is useful for identifying daemons.

LOG_CONSSend messages to the console if unable to send them to syslogd. This option is useful in daemon processes that have no controlling terminal. 

LOG_NDELAY
Open the connection to syslogd immediately, instead of when the first message is logged. This option is useful for programs that need to manage the order in which file descriptors are allocated. 

LOG_NOWAIT
Log messages to the console without waiting for child processes that are forked. Use this option for processes that enable notification of termination of child processes through SIGCHLD; otherwise, the syslog() function may block, waiting for a child process whose exit status has already been collected. 

facilitySpecifies the facility that generated the message, which is one of the following:

LOG_KERNMessages generated by the kernel. These cannot be generated by any user processes. 

LOG_USERMessages generated by user processes. This is the default facility when none is specified. 

LOG_MAILMessages generated by the mail system. 

LOG_DAEMON
Messages generated by system daemons.

LOG_AUTHMessages generated by the authorization system: login, su, and so on. 

LOG_LPRMessages generated by the line printer spooling system. 

LOG_RFSMessages generated by remote file systems. 

LOG_LOCAL0 through LOG_LOCAL7
Reserved for local use.

priorityMessages are tagged with codes indicating the type of priority for each.  The priority parameter is encoded as a facility (as listed above), which describes the part of the system generating the message, and as a level, which indicates the severity of the message.  The level of severity is selected from the following list:

A panic condition reported to all users.

LOG_ALERT
A condition to be corrected immediately; for example, a corrupted database.

LOG_CRITCritical conditions; for example, hard device errors. 

LOG_ERRErrors. 

LOG_WARNING
Warning messages.

LOG_NOTICE
Not an error condition, but a condition requiring special handling.

LOG_INFOGeneral information messages. 

LOG_DEBUG
Messages containing information useful to debug a program.

message [ value ... ]
Similar to the printf fmt string, with the difference that %m is replaced by the current error message obtained from errno. 

mask_priority
Specifies a bit mask used to set the new log priority mask and return the previous mask. The LOG_MASK and LOG_UPTO macros in the sys/syslog.h file are used to create the priority mask. 

DESCRIPTION

The syslog() function writes messages to the system log maintained by the syslogd daemon. 

The message parameter is similar to the printf() fmt string, with the difference that %m is replaced by the current error message obtained from errno.  A trailing new line can be added to the message if needed. The value parameters are the same as the value parameters of the printf() function. 

The syslogd daemon reads messages and writes them to the system console or to a log file, or forwards them to the syslogd daemon on the appropriate host. 

If syslog() cannot pass the message to syslogd, it writes the message on /dev/console, provided the LOG_CONS option is set. 

If special processing is required, the openlog() function can be used to initialize the log file.  The id parameter contains a string that is attached to the beginning of every message.  The facility parameter encodes a default facility from the previous list to be assigned to messages that do not have an explicit facility encoded. 

The closelog() function closes the log file. 

The setlogmask() function uses the bit mask in the mask_priority parameter to set the new log priority mask and returns the previous mask.  Logging is enabled for the levels indicated by the bits in the mask that are set and is disabled where the bits are not set. The default mask allows all priorities to be logged.  If the syslog() function is called with a priority mask that does not allow logging of that level of message, then the function returns without logging the message. 

RETURN VALUES

The syslog() function returns -1 if either the priority mask excludes this message from being logged, or if an error occurs and it is impossible to send the message to the syslogd daemon or to the system console. 

RELATED INFORMATION

Functions: profil(2)

Commands: cc(1)