mIRC already does save /list results to a file , but you have no control over its name when used from commandline, and it also overwrites the same file for each search. This switch is to supply mIRC with a optional filename to save to.
For example, as it is now, if you did "/list *orange*" on network1, and then "/list *linux*" on network2, the second list is saved to (overwrites) the same file, usually "channels.txt" when used from commandline. My proposal would allow /list -f *orange* "kofnet orange.txt" and /list -f *cafe* "blahnet cafes.txt", to save both searches.
Do you want it to save the output to a file?