This section describes blank() filter function in syslog-ng OSE.

Synopsis: blank(“MESSAGE”)

Description: The blank() filter selects messages where the specified key-value pair is considered blank. A value is considered blank if it meets any of the following conditions:

  • It is not set
  • It is an empty string (“”)
  • It contains only whitespace characters
  • It is an empty list
  • It is a boolean value explicitly set to false

Example: Select log messages where the field MESSAGE is blank

blank("MESSAGE")

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