Re: Interpretation of extensions different from Unix/Linux?

[Adam Beneschan <adam@irvine.com>]

On Aug 20, 12:44 pm, Robert A Duff <bobd...@shell01.TheWorld.com>
wrote:

> If I say, "cp *.ada backup", it means copy all the *.ada files
> into the backup directory.  Suppose I accidentally hit <enter>
> before typing "backup", so I say, "cp *.ada".  On a reasonable
> system, I'd get an error -- one argument passed, but 'cp' is
> expecting two.  On Unix, I usually get an error, but it's
> something nonsensical, like "zoo.ada is not a directory".
> And if it just so happens that there are exactly two files
> matching *.ada, I get no error -- instead of backing up
> my files, it destroys one of them!

Yup.  That last feature can be a bit of a blessing, though, at least
when you throw curly braces into the mix.  A file name like abc
{def,ghi,jkl}mno.ada is expanded by the shell to "abcdefmno.ada
abcghimno.ada abcjklmno.ada", which is helpful if you want to refer to
a set of files that differ only in parts of the names (or if you want
to specify a set of files in some other directory, so that you don't
have to type the path name repeatedly).  But I often abuse that
feature with commands like

   cp test1.ada{,.save}

The shell expands the latter to "test1.ada test1.ada.save" and doesn't
know that the two files it's expanding are going to have different
purposes in the command.  This is a little different from *, though,
in that it's not exactly a wild card, and will be expanded in the same
way with no regard to what files actually exist on your system.


> (Why is the "search" command called "grep"?  For that matter, why is the
> "help" command called "man"?)

Well, the second should be obvious---if you can't figure out how to do
what you want, you say, "Oh MAN, how do I use this *&^#@$*^
command???"

                                 -- Adam