: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`.
.. include:: ../includes/wasm-notavail.rst
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`,
:func:`openlog` will be called with no arguments.
.. audit-event:: syslog.syslog priority,message syslog.syslog
.. versionchanged:: 3.2
In previous versions, :func:`openlog` would not be called automatically if
it wasn't called prior to the call to :func:`syslog`, deferring to the syslog
implementation to call ``openlog()``.
.. 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.
.. audit-event:: syslog.openlog ident,logoption,facility syslog.openlog
.. versionchanged:: 3.2
In previous versions, keyword arguments were not allowed, and *ident* was
required.
.. 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.
.. audit-event:: syslog.closelog "" syslog.closelog
.. 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*.
.. audit-event:: syslog.setlogmask maskpri syslog.setlogmask
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...')
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