How to create log files with QIS?
To turn on log mode in QIS, pass -portlog as the command line option when launching QIS. The log file, qis.log_0, will be created in the startup directory or the directory set via Set_Working_Directory of QIS when a client connects to QIS. If a second client connects to the same QIS, another log file qis.log_1 will be created; a separate log file per connection. Once the log file is created, it will not be moved even if the working directory is changed via Set_Working_Directory.