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The
function writes 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 The message is identical to a format string,
except that is replaced by the current error message. (As denoted by the
global variable see A trailing newline is added if none is present. The
function is an alternate form in which the arguments have already been
captured using the variable-length argument facilities of The message
is tagged with Priorities are encoded as a and a The facility describes
the part of the system generating the message. The level is selected from
the following (high to low) list: A panic condition. This is normally
broadcast to all users. A condition that should be corrected immediately,
such as a corrupted system database. Critical conditions, e.g., hard device
errors. Errors. Warning messages. Conditions that are not error conditions,
but should possibly be handled specially. Informational messages. Messages
that contain information normally of use only when debugging a program.
The function provides for more specialized processing of the messages
sent by and The parameter is a string that will be prepended to every
message. The argument is a bit field specifying logging options, which
is formed by one or more of the following values: If cannot pass the
message to it will attempt to write the message to the console Open
the connection to 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. Write the message to standard error
output as well to the system log. Log the process id with each message:
useful for identifying instantiations of daemons. The parameter encodes
a default facility to be assigned to all messages that do not have an explicit
facility encoded: The authorization system: etc. The same as but
logged to a file readable only by selected individuals. The cron daemon:
System daemons, such as that are not provided for explicitly by other
facilities. The file transfer protocol daemon: Messages generated by
the kernel. These cannot be generated by any user processes. The line printer
spooling system: etc. The mail system. The network news system. Messages
generated internally by Messages generated by random user processes. This
is the default facility identifier if none is specified. The uucp system.
Reserved for local use. Similarly for through The function can be
used to close the log file. The function sets the log priority mask to
and returns the previous mask. Calls to with a priority not set in are
rejected. The mask for an individual priority is calculated by the macro
the mask for all priorities up to and including is given by the macro
The default allows all priorities to be logged.
The routines
and return no value. The routine always returns the previous log mask
level.
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");
These functions appeared in
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