Is there any tool to help me setup syntactically correct qsub command?

Yes, there exists an online tool qsub assembler.

Basically it is a form with a drop-down menu for every PBS resource type.

The only thing you need to do is to setup the value of selected resource(s) and click on the "Find machines" button.

As a result you will get

• a qsub command in a single-line format (to paste on CLI)
• dtto in a multi-line format of #PBS directives (to paste to the top section of batch script)
• a list of machines that comply with your criterions

The common confusion is that users try to remove the whole scratch directory

rm -rf $SCRATCHDIR

while they are allowed to remove only the content of the scratch directory:

rm -rf $SCRATCHDIR/*

The empty scratch directory will be removed automatically after some time.