: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.
.. availability:: Unix, not WASI, not iOS.
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:`~logging.handlers.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`,
: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()``.
.. versionchanged:: 3.12
This function is restricted in subinterpreters.
(Only code that runs in multiple interpreters is affected and
the restriction is not relevant for most users.)
:func:`openlog` must be called in the main interpreter before :func:`syslog` may be used
in a subinterpreter. Otherwise it will raise :exc:`RuntimeError`.
.. 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.
.. versionchanged:: 3.12
This function is restricted in subinterpreters.
(Only code that runs in multiple interpreters is affected and
the restriction is not relevant for most users.)
This may only be called in the main interpreter.
It will raise :exc:`RuntimeError` if called in a subinterpreter.
.. 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
.. versionchanged:: 3.12
This function is restricted in subinterpreters.
(Only code that runs in multiple interpreters is affected and
the restriction is not relevant for most users.)
This may only be called in the main interpreter.
It will raise :exc:`RuntimeError` if called in a subinterpreter.
.. 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:
.. data:: LOG_EMERG
LOG_ALERT
LOG_CRIT
LOG_ERR
LOG_WARNING
LOG_NOTICE
LOG_INFO
LOG_DEBUG
Priority levels (high to low).
.. data:: LOG_AUTH
LOG_AUTHPRIV
LOG_CRON
LOG_DAEMON
LOG_FTP
LOG_INSTALL
LOG_KERN
LOG_LAUNCHD
LOG_LPR
LOG_MAIL
LOG_NETINFO
LOG_NEWS
LOG_RAS
LOG_REMOTEAUTH
LOG_SYSLOG
LOG_USER
LOG_UUCP
LOG_LOCAL0
LOG_LOCAL1
LOG_LOCAL2
LOG_LOCAL3
LOG_LOCAL4
LOG_LOCAL5
LOG_LOCAL6
LOG_LOCAL7
Facilities, depending on availability in ``<syslog.h>`` for :const:`LOG_AUTHPRIV`,
:const:`LOG_FTP`, :const:`LOG_NETINFO`, :const:`LOG_REMOTEAUTH`,
:const:`LOG_INSTALL` and :const:`LOG_RAS`.
.. versionchanged:: 3.13
Added :const:`LOG_FTP`, :const:`LOG_NETINFO`, :const:`LOG_REMOTEAUTH`,
:const:`LOG_INSTALL`, :const:`LOG_RAS`, and :const:`LOG_LAUNCHD`.
.. data:: LOG_PID
LOG_CONS
LOG_NDELAY
LOG_ODELAY
LOG_NOWAIT
LOG_PERROR
Log options, depending on availability in ``<syslog.h>`` for
: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...')
Codebase Browser
cpython