list files but not directory
William Case
billlinux at rogers.com
Sat Aug 22 20:32:44 UTC 2009
Hi Marko;
On Sat, 2009-08-22 at 21:05 +0100, Marko Vojinovic wrote:
> > On Sat, Aug 22, 2009 at 03:59:30 -0400,
> > William Case <billlinux at rogers.com> wrote:
> > > All that I am saying is that it would be handy to have a simple util
> > > that listed file names. I suggest 'ls' because it is probably the most
> > > used and first learned listing utility and therefore would be the place
> > > to have it. It would be useful to beginners (particularly those who do
> > > not yet have any idea what a regexp is) and for script writing or piping
> > > to sed, awk, grep or a new file (or for appending).
>
> There is just one thing that baffles me here --- isn't a directory also a file?
> Given that, what you ask for is not an option to list only files, it is an
> option to list everything except directories. In other words, you are asking
> for an option that says "list the directory contents, but omit certain
> things".
>
> The more appropriate way to do this is to use some form of filtering. Such a
> thing does not naturally fit into a list of options of ls, IMHO. What you
> actually do is perform two operations here --- list the contents, and then
> filter it to display only some subset. Two operations should be done using two
> commands, the Unix Way. And the filtering approach gives you more flexibility
> what file types to filter out. For example, is /dev/sda a file or a directory?
> How would this hypothetical ls option behave in this case? List it or not?
>
> There are not *just directories and files* on the system. There are
> *just files*. And these files might be regular files, directories, devices,
> stdin/stdout, and who knows what else. You are proposing to add a single
> option to ls in order to filter out one of these types. Why only this one type?
> Put a whole bunch of options in ls which could list only regular files, or only
> character devices, or only hidden directories or... Or better yet, don't put
> any of that crap into ls, but pipe the ls output and filter it using a more
> appropriate tool.
>
> The completely analogous situation is with paging the output of ls. When I
> first used ls on a directory with lots of files, the natural idea for me was to
> look into its man page to find some option that would split the output into
> several screens and display them one by one. I failed to find such an option.
> After some digging, I found that this is done via a pipe to less:
>
> ls | less
>
> And then after some learning I understood that this is actually the better way
> to do it (more powerful, more flexible, more clean, more useful). The same
> situation is here with listing only non-directories.
>
> The main problem is not lack of functionality, but that Windows-converts have
> a frame of mind that makes a distinction between "directory" and "file"
> concepts, and believe these concepts are fundamentally different and non-
> overlapping.
That is exactly where I was coming from and believe that that defines
the problem the original poster had.
> This is a Bad Idea, and it seems more appropriate to educate
> users than to add options to ls which make it do things it is not designed
> for.
>
> Just remember: "Do one simple thing and do i well." ;-)
Marko, you have given the best explanation and counter argument yet to
this post.
However, I could tell you several (delightful) horror stories of hours
and hours I wasted when I first came to Linux from Windows. I bet there
are others who have had an equalling trying experience. Don't get me
wrong, Linux is by far the best operating system. But I still find
myself from time to time trying to solve problems by using 'MicroSoft
Intuition'. That usually means looking for a complex answer when, in
Linux, a simple answer will do.
In any case, I always keep my eye open for the newbies for whom
'intuition' is not working. They often get dismissed as if they should
know better.
I guess that all I was proposing was giving people some transitional
tools. To me, a regular file will always be a file different from the
others.
--
Regards Bill
Fedora 11, Gnome 2.26.3
Evo.2.26.3, Emacs 23.1.1
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