GNU bug report logs - #40903
the "ls -R *.pdf" command does not search recursively only current dir

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Message #12 received at 40903-done <at> debbugs.gnu.org (full text, mbox):

From: Eric Blake <eblake <at> redhat.com>
To: Jim Clark <jim.clark.ubuntu <at> gmail.com>, 40903-done <at> debbugs.gnu.org
Subject: Re: bug#40903: the "ls -R *.pdf" command does not search recursively
 only current dir
Date: Mon, 27 Apr 2020 10:00:52 -0500

tag 40903 notabug
thanks

On 4/27/20 9:25 AM, Jim Clark wrote:
> Greetings,
> 
> I found the ls command when used with a pattern does not search recursively.
> 
> ls -R *.pdf
> only searches the current directory and not recursively.

You are forgetting that globs expand prior to invoking ls.  What you 
have invoked is something like:

ls -R a.pdf b.pdf

which says to recursively list all files starting with a.pdf or b.pdf, 
and descending if any of those files are a directory, but neither a.pdf 
nor b.pdf is a directory, so there is nothing to descend into.

Instead of trying to mess with how globbing interacts with ls, you are 
better off learning how to use 'find', which does recursion and 
filtering as its primary goal.  In this case, you would use:

find . -name '*.pdf'

which gives you a recursive listing of all directories under '.', then 
filters it out to files ending in .pdf.

As the action of globbing is done by your shell and not by ls, there is 
nothing to change in coreutils, so I'm closing this as not a bug. But 
feel free to respond with further questions on the topic.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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