The areafill software includes a folder named examples in which we provide a sample script and a GDSII or OASIS files to test the software..
Here is how the batch file Demo looks like:

rm -f l2_simple*.tif all_perim*.tif layer2.txt all.txt
../bin/areafillmgr64 -h
#
# the -nfork:2 command line option has been added for consistency of the
# demo across different multi-core compute platforms
#
# when omitted it will default to one half the number of CPUs, e.g.
# for a 6 core machine areafillmgr64 will spawn 3 processes of the
# areafill engine
#
../bin/areafillmgr64 tiletest.gds layer2.txt = +2 -tile:50,50 -nfork:2
../bin/afill2tiff layer2.txt l2_simple

../bin/areafillmgr64 tiletest.gds all.txt = + -tile:50,50 -perimeter:xy -nfork:2
../bin/afill2tiff all.txt all_perim

Command Line Description

The areafillmgr64 reads the input file and based on the command line options, it will launch multiple areafill64 processes. In this example, -nfork:2 represents the number of areafill64 processes that should be spawned by the areafill manager.
When -nfork is being omitted, areafillmgr64 will default to one half the number of CPUs. For example: for a 6 core machine areafillmgr64 will spawn 3 processes of the areafill64 engine.

If you review the log file, you will notice that the areafillmgr64 starts two processes of the areafill64.
Once the areafill64 processes all complete, the areafillmgr64 will start the afill2tiff which will convert the text file to TIFF images.