Logging

The Message Queue C-API library uses two environment variables to control execution-time logging:

• MQ_LOG_FILE specifies the file to which log messages are directed. If you do not specify a file name for this variable, stderr is used. If MQ_LOG_FILE is a directory name, it should include a trailing directory separator.

  By default, .n (where n is 0, 1, 2,...) is appended to the actual log file name. This is used as a rotation index, and the indices are used sequentially when the maximum log file size is reached. You can use %g to specify a rotation index replacement in MQ_LOG_FILE after the last directory separator. Only the last %g is used if multiple %g’s are specified. the %g replacement can be escaped with %. The maximum rotation index is 9, and the maximum log file size is 1 MB. These limits are not configurable.

• MQ_LOG_LEVEL specifies a numeric level that indicates the detail of logging information needed:

  -1

  OFF, which suppresses the generation of log messages

  0

  SEVERE level, which indicates a severe failure

  1

  WARNING level, which indicates a potential problem

  2

  INFO level, for informational messages

  3

  CONFIG level, for static configuration messages

  4

  FINE level, which provides tracing information

  5

  FINER level, which provides detailed tracing information

  6

  FINEST level, which provides highly detailed tracing information

  For any value of MQ_LOG_LEVEL, log messages of that value or lower are generated. For example, setting MQ_LOG_LEVEL to 2 causes INFO, WARNING and SEVERE log messages to be generated.

  The default level is 3, CONFIG.