Apache Flink

Hi Team, Is there any way to set the name of the log file for flink JM and TM. I was able to find the env variable to change the default directory for logging(`env.log.dir`) but couldnt find out the respective variable for log file name.

You can set the file name (pattern) in the log4j config.
```appender.main.fileName = ${sys:log.file}
appender.main.filePattern = ${sys:log.file}.%i```

Mind you that changing this here will likely break the log display in the UI, since that relies on the `log.file` system property which is hard-coded in the startup scripts.

Also, after doing the said changes, i am able to see new file name under logs for task manager on ui, but cant see any log file for JM on UI. Is this expected?

It's not surprising, let's put it like that. The log display works quite differently between the JM and TM.

I expected the JM display to now work since IIRC it relies entirely on the `log.file` property, but I wasnt sure whether the TM display would be affected.