syslog — 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
logging.handlers module as SysLogHandler.
The module defines the following functions:
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 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 openlog() call is used.
If openlog() has not been called prior to the call to syslog(),
openlog() will be called with no arguments.
Raises an auditing event syslog.syslog with arguments priority, message.
Changed in version 3.2: In previous versions, openlog() would not be called automatically if
it wasn’t called prior to the call to syslog(), deferring to the syslog
implementation to call openlog().
Changed in version 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.)
openlog() must be called in the main interpreter before syslog() may be used
in a subinterpreter. Otherwise it will raise RuntimeError.
Logging options of subsequent syslog() calls can be set by calling
openlog(). syslog() will call 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 LOG_USER) sets the default facility for
messages which do not have a facility explicitly encoded.
Raises an auditing event syslog.openlog with arguments ident, logoption, facility.
Changed in version 3.2: In previous versions, keyword arguments were not allowed, and ident was required.
Changed in version 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 RuntimeError if called in a subinterpreter.
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, openlog() will be called on the first syslog() call (if
openlog() hasn’t already been called), and ident and other
openlog() parameters are reset to defaults.
Raises an auditing event syslog.closelog with no arguments.
Changed in version 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 RuntimeError if called in a subinterpreter.
Set the priority mask to maskpri and return the previous mask value. Calls
to 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.
Raises an auditing event syslog.setlogmask with argument maskpri.
The module defines the following constants:
Priority levels (high to low).
Facilities, depending on availability in <syslog.h> for LOG_AUTHPRIV,
LOG_FTP, LOG_NETINFO, LOG_REMOTEAUTH,
LOG_INSTALL and LOG_RAS.
Changed in version 3.13: Added LOG_FTP, LOG_NETINFO, LOG_REMOTEAUTH,
LOG_INSTALL, LOG_RAS, and LOG_LAUNCHD.
Log options, depending on availability in <syslog.h> for
LOG_ODELAY, LOG_NOWAIT and LOG_PERROR.
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...')