locate and updatedb

Buchbinder, Barry (NIH/NIAID) [E] BBuchbinder@niaid.nih.gov
Wed Feb 17 16:01:00 GMT 2016

Byron Boulton sent the following at Wednesday, February 17, 2016 8:43 AM
>On 2/16/2016 5:55 PM, Buchbinder, Barry (NIH/NIAID) [E] wrote:
>> This is technically OT since this involved a non-cygwin tool.
>> find is slow compared with a non-Cygwin tool, specifically dir (cmd.exe).
>> Compare find with cmd.exe's dir.  Note that even with the benefit of
>> caching (compare the 1st and 3rd times), find takes twice as long as dir.
>> Comparing cached times (2nd vs 3rd), dir is 3X faster.
>> $ time cmd /c dir /s /b 'C:\usr' > /dev/null ; \ time find /c/usr >
>> /dev/null ; \ time cmd /c dir /s /b 'C:\usr' > /dev/null
>> real    0m1.326s
>> user    0m0.000s
>> sys     0m0.047s
>> real    0m2.465s
>> user    0m0.280s
>> sys     0m2.184s
>> real    0m0.874s
>> user    0m0.000s
>> sys     0m0.031s
>> (Note: c:\usr has nothing to do with /usr.)
>> Here's how I use dir *in the abstract* for drives C: and D:.  (Note:
>> the
>> /a: option of dir lists all files, including hidden ones; /o:n sorts
>> by
>> name.)
>> for D in /c /d
>> do
>>      "$(cygpath "${COMSPEC}")" /c dir /s /b /a: /o:n "$(cygpath -w "$D")"
>> done | \
>> tr -s '\r\n' '\n' | \
>> cygpath -u -f - | \
>> sed -e '/^$/d' -e 's,/\+,/,g' \
>> sort -u \
>> /usr/libexec/frcode > /tmp/updatedb.tmp chmod --reference
>> /var/locatedb /tmp/updatedb.tmp mv /tmp/updatedb.tmp /var/locatedb
>> What I actually do (attached) is more complicated.  My script chooses
>> which directories are scanned, does them in parallel, and prints
>> pretty messages.  I get error messages for very long paths (> ~250
>> bytes).  It works well enough for me; YMMV.
>Are you using dir in some sort of custom way to build the database
>used by locate? Or are you saying that rather than ever using the find
>command to find files, you use a custom script which uses dir?

I use dir only to generate the locate database, because scanning the
better part of several disks takes so long.  I do not substitute dir for
find for other purposes.  One could, but usually locate does what I need,
and when it doesn't, I use find.

Best wishes,

- Barry
  Disclaimer: Statements made herein are not made on behalf of NIAID.

Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple

More information about the Cygwin mailing list