My the latest version of G'MIC (2.0.2), if I choose the conformal maps filter in the GIMP plug-in, I have this :
And if I set Output messages -> Verbose, then I get this command printed on the shell:
-fx_conformal_maps_preview 8,1,0,"((1.1 + i*z/6)/(1.04 - i*z/6))^6.2",0,0,0,0,0,3,0,0,"1024","1024"
You can see that each item in the argument list (separated by commas) corresponds exactly to one parameter in the plug-in (in the order they are displayed), so you can find the meaning of each argument like this.
Now, if you want to invoke this command from a shell like
bash , you'll need to also backslash the given quotes and parentheses, since those characters have already a meaning for
bash, so you can write something like this:
$ gmic -sp lena -fx_conformal_maps_preview 8,1,0,\"\(\(1.1 + i*z/6\)/\(1.04 - i*z/6\)\)^6.2\",0,0,0,0,0,3,0,0,\"1024\",\"1024\"