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Re: locate and updatedb

On 2/17/2016 11:00 AM, Buchbinder, Barry (NIH/NIAID) [E] wrote:
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:
/a: option of dir lists all files, including hidden ones; /o:n sorts

for D in /c /d
      "$(cygpath "${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.

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locate understands how to read this custom database? If I read you script properly, it produces a file which is just a sorted text file with one line per file found by


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