Hi,

Antony Stone <Antony.Stone@???> writes:

> On Saturday 23 April 2022 at 22:57:12, Florian Zieboll via Dng wrote:
>
>> On Sat, 23 Apr 2022 21:15:34 +0200 Antony Stone wrote:
>> > On Saturday 23 April 2022 at 21:11:18, Florian Zieboll via Dng wrote:
>> >
>> > > Some time ago, in a similar situation, I had been successful with
>> > >
>> > > $ find / | grep xorg.conf
>> >

>> > Personally I'd have gone for:
>> >     find / -name xorg.conf

>>
>> I may be wrong (and nitpicking;) - but I think that your approach is
>> less fast, as 'find' does the file name matching /before/ it continues
>> searching - in opposite to just piping its output to grep and going on
>> with running down the file system hierarchy without any interruption.
>
> Interesting - and you're right.
>
> I just tried several successive searches for a few unique filenames in a
> directory tree (all files in the same directory, just in case the position made
> a difference).
>
> The first search took 6 minutes and clearly set up some cache of results,
> because subsequent searches were consistently:
>

>     find . | grep filename : 20 seconds

>

>     find . -name filename : 25 seconds

>
> That was consistent no matter whether the two filenames were the same, or
> different but still in the same directory, and no matter which command was run
> first.
>
> Nice observation.

Indeed but you must have an awful lot of files, slow disks and/or a slow
network connection. After setting up the cache on my machine, I get 0.7
seconds for the -name approach and 0.5 seconds for grep.
That's with close to half a million filesystem entries and about 7000 of
those on an NFS backed filesystem on the NAS downstairs. The rest is on
an SSD (NVMe).

Another point, the grep approach also lists everything below a directory
that matches, whereas the -name approach does not. That may be a lot of
extra junk to scan through depending on what you're looking for.
That's also why I suggested redirecting errors to /dev/null when looking
for stuff below / as a normal user ;-)

Hope this helps,
--
Olaf Meeuwissen                    FSF Associate Member since 2004-01-27
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