:mod:syslog --- Unix syslog library routines

.. module:: syslog :platform: Unix :synopsis: An interface to the Unix syslog library routines.

This module provides an interface to the Unix syslog library routines. Refer to the Unix manual pages for a detailed description of the syslog facility.

This module wraps the system syslog family of routines. A pure Python library that can speak to a syslog server is available in the :mod:logging.handlers module as :class:SysLogHandler.

The module defines the following functions:

.. function:: syslog(message) syslog(priority, message)

Send the string message to the system logger. A trailing newline is added if necessary. Each message is tagged with a priority composed of a facility and a level. The optional priority argument, which defaults to :const:LOG_INFO, determines the message priority. If the facility is not encoded in priority using logical-or (LOG_INFO | LOG_USER), the value given in the :func:openlog call is used.

If :func:openlog has not been called prior to the call to :func:syslog, openlog() will be called with no arguments.

.. function:: openlog([ident[, logoption[, facility]]])

Logging options of subsequent :func:syslog calls can be set by calling :func:openlog. :func:syslog will call :func:openlog with no arguments if the log is not currently open.

The optional ident keyword argument is a string which is prepended to every message, and defaults to sys.argv[0] with leading path components stripped. The optional logoption keyword argument (default is 0) is a bit field -- see below for possible values to combine. The optional facility keyword argument (default is :const:LOG_USER) sets the default facility for messages which do not have a facility explicitly encoded.

.. versionchanged:: 3.2 In previous versions, keyword arguments were not allowed, and ident was required. The default for ident was dependent on the system libraries, and often was python instead of the name of the Python program file.

.. function:: closelog()

Reset the syslog module values and call the system library closelog().

This causes the module to behave as it does when initially imported. For example, :func:openlog will be called on the first :func:syslog call (if :func:openlog hasn't already been called), and ident and other :func:openlog parameters are reset to defaults.

.. function:: setlogmask(maskpri)

Set the priority mask to maskpri and return the previous mask value. Calls to :func:syslog with a priority level not set in maskpri are ignored. The default is to log all priorities. The function LOG_MASK(pri) calculates the mask for the individual priority pri. The function LOG_UPTO(pri) calculates the mask for all priorities up to and including pri.

The module defines the following constants:

Priority levels (high to low): :const:LOG_EMERG, :const:LOG_ALERT, :const:LOG_CRIT, :const:LOG_ERR, :const:LOG_WARNING, :const:LOG_NOTICE, :const:LOG_INFO, :const:LOG_DEBUG.

Facilities: :const:LOG_KERN, :const:LOG_USER, :const:LOG_MAIL, :const:LOG_DAEMON, :const:LOG_AUTH, :const:LOG_LPR, :const:LOG_NEWS, :const:LOG_UUCP, :const:LOG_CRON, :const:LOG_SYSLOG, :const:LOG_LOCAL0 to :const:LOG_LOCAL7, and, if defined in <syslog.h>, :const:LOG_AUTHPRIV.

Log options: :const:LOG_PID, :const:LOG_CONS, :const:LOG_NDELAY, and, if defined in <syslog.h>, :const:LOG_ODELAY, :const:LOG_NOWAIT, and :const:LOG_PERROR.

Examples

Simple example

A simple set of examples::

   import syslog

   syslog.syslog('Processing started')
   if error:
       syslog.syslog(syslog.LOG_ERR, 'Processing started')

An example of setting some log options, these would include the process ID in
logged messages, and write the messages to the destination facility used for
mail logging::

   syslog.openlog(logoption=syslog.LOG_PID, facility=syslog.LOG_MAIL)
   syslog.syslog('E-mail processing initiated...')