# How do I tell Modelsim to not create a wlf file when I carry out simulation?

The wlf file contains the wave dump data. For some reason I get this message on my computer:

#           File in use by: leader  Hostname: DESKTOP-LEADER7  ProcessID: 14602
#
#           Attempting to use alternate WLF file "./wlftnzmqtm".
# ** Warning: (vsim-WLF-5001) Could not open WLF file: vsim.wlf
#
#           Using alternate file: ./wlftnzmqtm


Why it can't open the file I do not know. Basically I have commands to compile all files and then invoke vsim. I just invoke these .do files and soon I start seeing this error. I just want Modelsim to stop creating wlf files as I do not need them and because of this error, Modelsim ends up creating a lot of wlf files.

• A workaround for suppressing the generation of the wlf file is to use the -novopt option in vsim, vsim -novopt <design>. If you need to generate a wlf file with a specific name, use vsim -novopt -wlf <wave_file> <design>. – rvkrysh Feb 12 '18 at 8:27
• novopt has to do with optimization right? How is that linked to the wlf file? – quantum231 Feb 13 '18 at 10:23
• Yes. novopt is to turn off optimizations. However, I have seen that it also suppresses the wlf generation. When using novopt, you will have to use the wlf option specifically in order to generate the wave file. This may not be a solution for your problem, but will allow you to continue your simulations without the error. – rvkrysh Feb 13 '18 at 15:56