Re: find negation operator not working as expected

In article <ee3e5959-ce52-4e7d-ab51-c178b9513ad1@bi2g2000vbb.googlegroups.com>,
matt  <[email protected]> wrote:
>I'm trying to find all the files that don't contain a string in the
>current directory.  This incantation
>
>find . -exec grep -l "foobaz" '{}' \;

grep -l is printing the matching filenames because that's what grep -l does.
find is not printing anything because it doesn't print unless you ask it to
with -print. (In some cases, with a sufficiently new version of find, there
is an implicit -print but this isn't one of those cases.) The -exec does
produce a true/false result based on the exit value of the grep command, but
you're not using that result because the -exec is the last thing in your find
command.

>
>will list all the files that contain "foobaz"; however, when I try to
>invert this using any one of these incantations
>
>find . ! -exec grep -l "foobaz" '{}' \;

Now you've got the same grep command, still printing the same thing it did
before: the matching filenames. find is now getting a true/false result from
the -exec, and inverting it, and then doing nothing with it.

>find . \! -exec grep -l "foobaz" '{}' \;
>find . -not -exec grep -l "foobaz" '{}' \;
>
>I get the same output.  What's going on here?
>
>I'm using a bash shell on darwin Mac OS.  The "find" utility I'm using
>is the GNU variety built using MacPorts.

If you have GNU grep, then grep -L is what you want. It is the inverse of
grep -l.

If you want to use only minimal standard grep and find features, you need to
do 2 things: make find print the files that failed the -exec, and make grep
just return an exit value without printing anything. That would look like
this:

find . ! -exec grep -q foobaz '{}' \; -print

I'd also stick a -type f on the front, so you don't try to grep a directory.
grepping a directory is Not Good, even if GNU grep fails to complain about
it.

-- 
Alan Curry