cpython/Doc/library/syslog.rst

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: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`` module. 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([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[, logopt[, 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 *logopt* keyword argument
(default=0) is a bit field - see below for possible values to combine.
The optional *facility* keyword argument (default=: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` and :const:`LOG_LOCAL0` to :const:`LOG_LOCAL7`.
Log options:
:const:`LOG_PID`, :const:`LOG_CONS`, :const:`LOG_NDELAY`, :const:`LOG_NOWAIT`
and :const:`LOG_PERROR` if defined in ``<syslog.h>``.
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(logopt=syslog.LOG_PID, facility=syslog.LOG_MAIL)
syslog.syslog('E-mail processing initiated...')