Standard C Library Functions syslog(3C)
NAME
syslog, openlog, closelog, setlogmask - control system log
SYNOPSIS
#include
void openlog(const char *ident, int logopt, int facility);void syslog(int priority, const char *message, .../* arguments */);
void closelog(void); int setlogmask(int maskpri);DESCRIPTION
The syslog() function sends a message to syslogd(1M), which,
depending on the configuration of /etc/syslog.conf, logs it
in an appropriate system log, writes it to the system con-
sole, forwards it to a list of users, or forwards it to sys-
logd on another host over the network. The logged message includes a message header and a message body. The message header consists of a facility indicator, a severity level indicator, a timestamp, a tag string, and optionally the process ID. The message body is generated from the message and following arguments in the same manner as if these were arguments toprintf(3C), except that occurrences of %m in the format
string pointed to by the message argument are replaced by the error message string associated with the current value of errno. A trailing NEWLINE character is added if needed.Symbolic constants for use as values of the logopt, facil-
ity, priority, and maskpri arguments are defined in theValues of the priority argument are formed by ORing together a severity level value and an optional facility value. If no facility value is specified, the current default facility value is used. Possible values of severity level include, in decreasing order:
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Standard C Library Functions syslog(3C)
LOG_EMERG A panic condition. This is normally broad-
cast to all users.LOG_ALERT A condition that should be corrected immedi-
ately, such as a corrupted system database.LOG_CRIT Critical conditions, such as hard device
errors.LOG_ERR Errors.
LOG_WARNING Warning messages.
LOG_NOTICE Conditions that are not error conditions, but
that may require special handling.LOG_INFO Informational messages.
LOG_DEBUG Messages that contain information normally of
use only when debugging a program. The facility indicates the application or system component generating the message. Possible facility values include:LOG_KERN Messages generated by the kernel. These cannot
be generated by any user processes.LOG_USER Messages generated by random user processes.
This is the default facility identifier if none is specified.LOG_MAIL The mail system.
LOG_DAEMON System daemons, such as in.ftpd(1M).
LOG_AUTH The authentication / security / authorization
system: login(1), su(1M), getty(1M).SunOS 5.11 Last change: 16 Mar 2009 2
Standard C Library Functions syslog(3C)
LOG_LPR The line printer spooling system: lpr(1B),
lpc(1B).LOG_NEWS Designated for the USENET network news system.
LOG_UUCP Designated for the UUCP system; it does not
currently use syslog().
LOG_CRON The cron/at facility; crontab(1), at(1),
cron(1M).LOG_AUDIT The audit facility, for example, auditd(1M).
LOG_LOCAL0 Designated for local use.
LOG_LOCAL1 Designated for local use.
LOG_LOCAL2 Designated for local use.
LOG_LOCAL3 Designated for local use.
LOG_LOCAL4 Designated for local use.
LOG_LOCAL5 Designated for local use.
LOG_LOCAL6 Designated for local use.
LOG_LOCAL7 Designated for local use.
The openlog() function sets process attributes that affectsubsequent calls to syslog(). The ident argument is a string
that is prepended to every message. The openlog() functionuses the passed-in ident argument directly, rather than mak-
ing a private copy of it. The logopt argument indicates log-
ging options. Values for logopt are constructed by abitwise-inclusive OR of zero or more of the following:
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Standard C Library Functions syslog(3C)
LOG_PID Log the process ID with each message. This is
useful for identifying specific daemon processes (for daemons that fork).LOG_CONS Write messages to the system console if they
cannot be sent to syslogd(1M). This option is
safe to use in daemon processes that have nocontrolling terminal, since syslog() forks
before opening the console.LOG_NDELAY Open the connection to syslogd(1M) immedi-
ately. Normally the open is delayed until the first message is logged. This is useful for programs that need to manage the order in which file descriptors are allocated.LOG_ODELAY Delay open until syslog() is called.
LOG_NOWAIT Do not wait for child processes that have been
forked to log messages onto the console. This option should be used by processes that enable notification of child termination usingSIGCHLD, since syslog() may otherwise block
waiting for a child whose exit status has already been collected. The facility argument encodes a default facility to beassigned to all messages that do not have an explicit facil-
ity already encoded. The initial default facility isLOG_USER.
The openlog() and syslog() functions may allocate a file
descriptor. It is not necessary to call openlog() prior tocalling syslog().
The closelog() function closes any open file descriptorsallocated by previous calls to openlog() or syslog().
The setlogmask() function sets the log priority mask for the current process to maskpri and returns the previous mask. If the maskpri argument is 0, the current log mask is notmodified. Calls by the current process to syslog() with a
priority not set in maskpri are rejected. The mask for anSunOS 5.11 Last change: 16 Mar 2009 4
Standard C Library Functions syslog(3C)
individual priority pri is calculated by the macroLOG_MASK(pri); the mask for all priorities up to and includ-
ing toppri is given by the macro LOG_UPTO(toppri). The
default log mask allows all priorities to be logged.RETURN VALUES
The setlogmask() function returns the previous log prioritymask. The closelog(), openlog() and syslog() functions
return no value.ERRORS
No errors are defined.EXAMPLES
Example 1 Example of LOG_ALERT message.
This call logs a message at priority LOG_ALERT:
syslog(LOG_ALERT, "who: internal error 23");
The FTP daemon ftpd would make this call to openlog() toindicate that all messages it logs should have an identify-
ing string of ftpd, should be treated by syslogd(1M) as
other messages from system daemons are, should include the process ID of the process logging the message:openlog("ftpd", LOG_PID, LOG_DAEMON);
Then it would make the following call to setlogmask() toindicate that messages at priorities from LOG_EMERG through
LOG_ERR should be logged, but that no messages at any other
priority should be logged:setlogmask(LOG_UPTO(LOG_ERR));
Then, to log a message at priority LOG_INFO, it would make
the following call to syslog:
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Standard C Library Functions syslog(3C)
syslog(LOG_INFO, "Connection from host %d", CallingHost);
A locally-written utility could use the following call to
syslog() to log a message at priority LOG_INFO to be treated
by syslogd(1M) as other messages to the facility LOG_LOCAL2
are:syslog(LOG_INFO|LOG_LOCAL2, "error: %m");
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | Safe |
|_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
SEE ALSO
at(1), crontab(1), logger(1), login(1), lpc(1B), lpr(1B), auditd(1M), cron(1M), getty(1M), in.ftpd(1M), su(1M),syslogd(1M), printf(3C), syslog.conf(4), attributes(5),
standards(5)SunOS 5.11 Last change: 16 Mar 2009 6