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Python Syslog Module

The syslog module provides an interface to the Unix syslog library routines. This module is intended to be used for logging system messages on Unix systems.

Note: This module is only available on Unix.

Importing the Module

import syslog

Basic Logging

You can log a message using syslog.syslog().

import syslog

syslog.syslog('Processing started')

You can also specify the priority level.

syslog.syslog(syslog.LOG_WARNING, 'This is a warning')
syslog.syslog(syslog.LOG_ERR, 'This is an error')

Priorities

The module defines the following priority levels (from highest to lowest):

  • LOG_EMERG: System is unusable.
  • LOG_ALERT: Action must be taken immediately.
  • LOG_CRIT: Critical conditions.
  • LOG_ERR: Error conditions.
  • LOG_WARNING: Warning conditions.
  • LOG_NOTICE: Normal but significant condition.
  • LOG_INFO: Informational.
  • LOG_DEBUG: Debug-level messages.

Opening and Closing Logs

You can customize how the log is opened using openlog().

syslog.openlog(ident, logoption, facility)

  • ident: A string that is prepended to every message (defaults to sys.argv[0]).
  • logoption: Bit field options (e.g., LOG_PID, LOG_CONS).
  • facility: The type of program logging the message.
import syslog
import os

syslog.openlog(ident="my_app", logoption=syslog.LOG_PID, facility=syslog.LOG_LOCAL0)
syslog.syslog("Message from my_app")
syslog.closelog()

Setting the Log Mask

You can restrict which priorities are logged using setlogmask().

import syslog

# Only log warnings and errors (and higher)
syslog.setlogmask(syslog.LOG_UPTO(syslog.LOG_WARNING))

syslog.syslog(syslog.LOG_WARNING, "This will be logged")
syslog.syslog(syslog.LOG_INFO, "This will NOT be logged")

programming/python/python

Created: March 17, 2026 • Last Modified: January 27, 2026