I want to use a single log file defined by a property in "kettle.properties" (system-wide available variable). This is an exact path and extension of log file.

Using default "Write to log" uses this file perfectly.

But when using customized writing to log by "Add constants" for log message and "Write to file" to write the log, it creates a new file and appends "_0" to it.

For example:

Original log file name: kettle.log
Additional log file name: kettle_0.log

Why is this? Does spoon lock the original log file when running? Is the additional log file created because of that?