syslog(3) - NetBSD Manual Pages

SYSLOG(3)                 NetBSD Programmer's Manual                 SYSLOG(3)


NAME
syslog, vsyslog, openlog, closelog, setlogmask - control system log
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <syslog.h> void syslog(int priority, const char *message, ...); void openlog(const char *ident, int logopt, int facility); void closelog(void); int setlogmask(int maskpri); #include <stdarg.h> void vsyslog(int priority, const char *message, va_list args);
DESCRIPTION
The syslog() function writes message to the system message logger. The message is then written to the system console, log files, logged-in users, or forwarded to other machines as appropriate (See syslogd(8)). The message is identical to a printf(3) format string, except that `%m' is replaced by the current error message. (As denoted by the global vari- able errno; see strerror(3).) A trailing newline is added if none is pre- sent. The vsyslog() function is an alternative form in which the arguments have already been captured using the variable-length argument facilities of varargs(3). The message is tagged with priority. Priorities are encoded as a facility and a level. The facility describes the part of the system gen- erating the message. The level is selected from the following ordered (high to low) list: LOG_EMERG A panic condition. This is normally broadcast to all users. LOG_ALERT A condition that should be corrected immediately, such as a corrupted system database. LOG_CRIT Critical conditions, e.g., hard device errors. LOG_ERR Errors. LOG_WARNING Warning messages. LOG_NOTICE Conditions that are not error conditions, but should possi- bly be handled specially. LOG_INFO Informational messages. LOG_DEBUG Messages that contain information normally of use only when debugging a program. The openlog() function provides for more specialized processing of the messages sent by syslog() and vsyslog(). The parameter ident is a string that will be prepended to every message. The logopt argument is a bit field specifying logging options, which is formed by OR'ing one or more of the following values: LOG_CONS If syslog() cannot pass the message to syslogd(8) it will attempt to write the message to the console (``/dev/console''). LOG_NDELAY Open the connection to syslogd(8) immediately. Normally the open is delayed until the first message is logged. Useful for programs that need to manage the order in which file descriptors are allocated. LOG_PERROR Write the message to standard error output as well to the system log. LOG_PID Log the process id with each message: useful for identify- ing instantiations of daemons. The facility parameter encodes a default facility to be assigned to all messages that do not have an explicit facility encoded: LOG_AUTH The authorization system: login(1), su(1), getty(8), etc. LOG_AUTHPRIV The same as LOG_AUTH, but logged to a file readable only by selected individuals. LOG_CRON The cron daemon: cron(8). LOG_DAEMON System daemons, such as routed(8), that are not provided for explicitly by other facilities. LOG_FTP The file transfer protocol daemon: ftpd(8). LOG_KERN Messages generated by the kernel. These cannot be generat- ed by any user processes. LOG_LPR The line printer spooling system: lpr(1), lpc(8), lpd(8), etc. LOG_MAIL The mail system. LOG_NEWS The network news system. LOG_SYSLOG Messages generated internally by syslogd(8). LOG_USER Messages generated by random user processes. This is the default facility identifier if none is specified. LOG_UUCP The uucp system. LOG_LOCAL0 Reserved for local use. Similarly for LOG_LOCAL1 through LOG_LOCAL7. The closelog() function can be used to close the log file. The setlogmask() function sets the log priority mask to maskpri and re- turns the previous mask. Calls to syslog() with a priority not set in maskpri are rejected. The mask for an individual priority pri is calcu- lated by the macro LOG_MASK(pri); the mask for all priorities up to and including toppri is given by the macro LOG_UPTO(toppri);. The default allows all priorities to be logged.
RETURN VALUES
The routines closelog(), openlog(), syslog() and vsyslog() return no val- ue. The routine setlogmask() always returns the previous log mask level.
EXAMPLES
syslog(LOG_ALERT, "who: internal error 23"); openlog("ftpd", LOG_PID | LOG_NDELAY, LOG_FTP); setlogmask(LOG_UPTO(LOG_ERR)); syslog(LOG_INFO, "Connection from host %d", CallingHost); syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m");
SEE ALSO
logger(1), syslogd(8)
HISTORY
These functions appeared in 4.2BSD. NetBSD 1.6.1 March 14, 2001 3

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