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Spotlight, mdfind (Mac OS X Tiger searching)

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Most users will probably see Spotlight as an enhanced, very fast file searcher: something that builds an index of files and their contents, and can very quickly search that index and return results.

Actually, Spotlight is much, much more than that, but if that’s all you need, it sure beats “find” and “grep”. That’s true even if all we are talking about is finding text.

I’m not a bit interested in the GUI interface to Spotlight. It’s fine for what it is, but the command line “mdfind” is much more interesting. But before we get to that, let’s look at where Spotlight stores its index:

$ sudo bash
# pwd
/.Spotlight-V100
# ls -l
total 183136
-rw------- 1 root admin 0 May 6 14:59 .journalHistoryLog
-rw------- 1 root admin 32591872 May 6 15:02 .store.db
-rw------- 1 root admin 28573696 May 6 14:55 ContentIndex.db
-rw------- 1 root admin 391 May 6 14:59 _exclusions.plist
-rw------- 1 root admin 378 May 1 20:34 _rules.plist
-rw------- 1 root admin 32591872 May 6 15:02 store.db
# cat _exclusions.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
      <key>EXCLUSIONS</key>
      <array>
           <string>/Users/apl/snapshots</string>
           <string>/Users/apl/Movies</string>
           <string>/Users/apl/Music</string>
           <string>/Users/apl/Pictures</string>
      </array>
</dict>
</plist>
#

Notice the EXCLUSIONS list? You can add to that with the System Preferences tool, but this is where it is actually stored. However, as we’ll see in a moment, this is NOT all that Spotlight (and mdfind) ignores. You need to be aware of that when using mdfind.

For the simplest use, just do “mdfind whatever”. Can you use that in a script? Why not?

for i in `mdfind Stuff`
do
   scp $i me@somewhere.com:$i
done

But mdfind is much more powerful than that:

mdfind 'kMDItemTextContent == "*Seneca*" && kMDItemFSName != "*emlx"'
mdfind 'kMDItemTextContent == "*Seneca*" && kMDItemContentType != "com.apple.mail.emlx"'

That’s searching metadata. What metadata can you search? Well, anything that’s available and “mdls” will show you that:

$ mdls t.txt
t.txt -------------
kMDItemAttributeChangeDate = 2005-05-06 15:44:32 -0400
kMDItemContentCreationDate = 2003-12-15 18:11:55 -0500
kMDItemContentModificationDate = 2005-05-06 15:44:31 -0400
kMDItemContentType = "public.plain-text"
kMDItemContentTypeTree = (
"public.plain-text",
"public.text",
"public.data",
"public.item",
"public.content"
)
kMDItemDisplayName = "t.txt"
kMDItemFSContentChangeDate = 2005-05-06 15:44:31 -0400
kMDItemFSCreationDate = 2003-12-15 18:11:55 -0500
kMDItemFSCreatorCode = 0
kMDItemFSFinderFlags = 0
kMDItemFSInvisible = 0
kMDItemFSLabel = 0
kMDItemFSName = "t.txt"
kMDItemFSNodeCount = 0
kMDItemFSOwnerGroupID = 20
kMDItemFSOwnerUserID = 501
kMDItemFSSize = 2552
kMDItemFSTypeCode = 0
kMDItemID = 1802523
kMDItemKind = "Plain text document"
kMDItemLastUsedDate = 2003-12-15 18:11:55 -0500
kMDItemUsedDates = (2003-12-15 18:11:55 -0500)

What mdls (and thus mdfind) sees can change:

$ mdls z
z -------------
kMDItemAttributeChangeDate = 2005-05-06 16:30:56 -0400
kMDItemContentCreationDate = 2004-06-08 13:06:19 -0400
kMDItemContentModificationDate = 2005-05-06 16:30:55 -0400
kMDItemContentType = "public.data"
kMDItemContentTypeTree = ("public.data", "public.item")
kMDItemDisplayName = "Z"
kMDItemFSContentChangeDate = 2005-05-06 16:30:55 -0400
kMDItemFSCreationDate = 2004-06-08 13:06:19 -0400
kMDItemFSCreatorCode = 0
kMDItemFSFinderFlags = 0
kMDItemFSInvisible = 0
kMDItemFSLabel = 0
kMDItemFSName = "Z"
kMDItemFSNodeCount = 0
kMDItemFSOwnerGroupID = 20
kMDItemFSOwnerUserID = 501
kMDItemFSSize = 2552
kMDItemFSTypeCode = 0
kMDItemID = 2434137
kMDItemKind = "Document"
kMDItemLastUsedDate = 2004-06-08 13:08:16 -0400
kMDItemUsedDates = (2004-06-08 13:08:16 -0400)

Permissions can also affect metadata, which in turn changes how Spotlight and mdfind see a file:

$ diff t t.txt
$ ls -l t t.txt
-rwxr-xr-x 1 apl staff 2552 May 6 15:41 t
-rw-r--r-- 1 apl staff 2552 May 6 15:44 t.txt
$ mdls t
t -------------
kMDItemAttributeChangeDate = 2005-05-06 15:41:14 -0400
kMDItemContentCreationDate = 2005-05-06 15:41:11 -0400
kMDItemContentModificationDate = 2005-05-06 15:41:11 -0400
kMDItemContentType = "public.data"
kMDItemContentTypeTree = ("public.data", "public.item")
kMDItemDisplayName = "t"
kMDItemFSContentChangeDate = 2005-05-06 15:41:11 -0400
kMDItemFSCreationDate = 2005-05-06 15:41:11 -0400
kMDItemFSCreatorCode = 0
kMDItemFSFinderFlags = 0
kMDItemFSInvisible = 0
kMDItemFSLabel = 0
kMDItemFSName = "t"
kMDItemFSNodeCount = 0
kMDItemFSOwnerGroupID = 20
kMDItemFSOwnerUserID = 501
kMDItemFSSize = 2552
kMDItemFSTypeCode = 0
kMDItemID = 5482482
kMDItemKind = "Unix Executable File"
kMDItemLastUsedDate = 2005-05-06 15:41:11 -0400
kMDItemUsedDates = (2005-05-06 15:41:11 -0400)

I put the string “fogpr1″ in a file, and then copied it to a few different names. Using “grep” finds all of them, but “mdfind” does not:

$ grep -l fogpr1 *
Z
abcde
abcde.doc
abcde.doh
abcde.txt
foo.txt
t
t.txt
$ mdfind fogpr1
/Users/apl/t.txt
/Users/apl/abcde.txt
/Users/apl/foo.txt

Spotlight and mdfind also ignore “.” files, even if you have told Finder not to ignore them:

$ defaults write com.apple.finder AppleShowAllFiles TRUE
$ killall Finder

For more technical information on Spotlight and mdfind, see http://arstechnica.com/reviews/os/macosx-10.4.ars/9 and http://developer.apple.com/macosx/spotlight.html.

*Originally published at APLawrence.com

A.P. Lawrence provides SCO Unix and Linux consulting services http://www.pcunix.com

Spotlight, mdfind (Mac OS X Tiger searching)
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