When I use command line options that are not valid Calibre won't directly point me to the option/options that is/are invalid. Instead it simply spits out the entire help message.
E.g. calibre -64 -gui -drc -runset x/y/z.runset
I happened to type the line above. I am very much used to typing "-64" along with "calibre" invariably all the time...and I just did that while invoking calibre interactive too. But "-64" apparently is not a valid option when used along with "-gui" option. Calibre could have easily given this direct pointer, but it never did. Every time I typed the line above, it simply spit out the help message ( "Usage" ...with all valid command line options) but that never helped me. I was doubting the runset, path to the runset etc. and spent quite some time there wondering what was wrong with those arguments. Only after a while I tried removing "-64" and saw it working. This is something very very simple...silly. Can't quite believe that Calibre is behaving this way...