15.4 What if a Wildcard Doesn't Match?

I ran into a strange situation the other day. I was compiling a program that was core dumping (52.9). At some point, I decided to delete the object files and the core file, and start over, so I gave the command:

% rm *.o core

It works as expected most of the time, except when no object files exist. (I don't remember why I did this, but it was probably by using !! (11.7) when I knew there weren't any .o's around.) In this case, you get No match, and the core file is not deleted.

It turns out, for C shell users, that if none of the wildcards can be expanded, you get a No match error. It doesn't matter that there's a perfectly good match for other name(s). That's because, when csh can't match a wildcard, it aborts and prints an error - it won't run the command. If you create one .o file or remove the *.o from the command line, core will disappear happily.

On the other hand, if the Bourne shell can't match a wildcard, it just passes the unmatched wildcard and other filenames:

*.o core

to the command (in this case, to rm) and lets the command decide what to do with it. So, with Bourne shell, what happens will depend on what your command does when it sees the literal characters *.o.

You can make csh act a lot like sh by using:

set nonomatch