Re: getting 'grepped' files from file list

[Bob Proulx]

Edward Peschko wrote:
> I've been going through my work habits, trying to pick out
> annoyances, inefficiencies etc, and one of the big ones
> I've come across is running into 'arg list too long' errors.

Of course there is an FAQ on this:

  
http://www.gnu.org/software/coreutils/faq/coreutils-faq.html#Argument-list-too-long

Specifically this recent change to the linux kernel would be
interesting to you.

  
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b6a2fea39318e43fee84fa7b0b90d68bed92d2ba

  mm: variable length argument support

  Remove the arg+env limit of MAX_ARG_PAGES by copying the strings
  directly from the old mm into the new mm.

So if you are patient enough you won't have to worry about it in the
future.

> One of the big culprits for this is grep. I try to pass a too long
> list, and get that error..

I imagine this will be due to expanson of file arguments?  In which
case you should, or at least could, use find.

  find . -type f -exec grep PATTERN {} +

But grep does have built in recursion support.  Even though I
personally believe it shouldn't because it violates the unix
philosophy and isn't needed since it is already in find.

  grep -r PATTERN .

> I know that xargs, etc. can get around this error but it
> is a pain to remember the syntax for this, and I
> don't think it can quite duplicate an integrated argument.

Using xargs with zero terminated strings works perfectly well.  But it
isn't standard and so can't be used portably.

> So I was wondering if a patch, giving a file containing a
> filelist would be accepted for the next version of grep?

Obviously by my response I don't think something like that is needed.
Is there a reason that you can't use one of the several existing
methods?  Can you provide some examples where not having this feature
is significantly problematic?

Bob