Ubuntu – Does linux filesystem support fast file searching /indexing

You can try recoll, it is available in the repositories, it gives you a lot of control over the folders you want to index and search and where you want to store the index database, you can use multiple databases too, you can use the advanced search to return results from a specific folder.

See some of its features here, You can run it from the command line passing the query and other control terms to it, see the short manual here. Here the full manual.

FSlint is a versatile duplicate finder that includes a function for finding duplicate names:

The FSlint package for Ubuntu emphasizes the graphical interface, but as is explained in the FSlint FAQ a command-line interface is available via the programs in /usr/share/fslint/fslint/. Use the --help option for documentation, e.g.:

$ /usr/share/fslint/fslint/fslint --help
File system lint.
A collection of utilities to find lint on a filesystem.
To get more info on each utility run 'util --help'.

findup -- find DUPlicate files
findnl -- find Name Lint (problems with filenames)
findu8 -- find filenames with invalid utf8 encoding
findbl -- find Bad Links (various problems with symlinks)
findsn -- find Same Name (problems with clashing names)
finded -- find Empty Directories
findid -- find files with dead user IDs
findns -- find Non Stripped executables
findrs -- find Redundant Whitespace in files
findtf -- find Temporary Files
findul -- find possibly Unused Libraries
zipdir -- Reclaim wasted space in ext2 directory entries
$ /usr/share/fslint/fslint/findsn --help
find (files) with duplicate or conflicting names.
Usage: findsn [-A -c -C] [[-r] [-f] paths(s) ...]

If no arguments are supplied the $PATH is searched for any redundant
or conflicting files.

-A reports all aliases (soft and hard links) to files.
If no path(s) specified then the $PATH is searched.

If only path(s) specified then they are checked for duplicate named
files. You can qualify this with -C to ignore case in this search.
Qualifying with -c is more restictive as only files (or directories)
in the same directory whose names differ only in case are reported.
I.E. -c will flag files & directories that will conflict if transfered
to a case insensitive file system. Note if -c or -C specified and
no path(s) specifed the current directory is assumed.

Example usage:

$ /usr/share/fslint/fslint/findsn /usr/share/icons/ > icons-with-duplicate-names.txt
$ head icons-with-duplicate-names.txt 
-rw-r--r-- 1 root root    683 2011-04-15 10:31 Humanity-Dark/AUTHORS
-rw-r--r-- 1 root root    683 2011-04-15 10:31 Humanity/AUTHORS
-rw-r--r-- 1 root root  17992 2011-04-15 10:31 Humanity-Dark/COPYING
-rw-r--r-- 1 root root  17992 2011-04-15 10:31 Humanity/COPYING
-rw-r--r-- 1 root root   4776 2011-03-29 08:57 Faenza/apps/16/DC++.xpm
-rw-r--r-- 1 root root   3816 2011-03-29 08:57 Faenza/apps/22/DC++.xpm
-rw-r--r-- 1 root root   4008 2011-03-29 08:57 Faenza/apps/24/DC++.xpm
-rw-r--r-- 1 root root   4456 2011-03-29 08:57 Faenza/apps/32/DC++.xpm
-rw-r--r-- 1 root root   7336 2011-03-29 08:57 Faenza/apps/48/DC++.xpm
-rw-r--r-- 1 root root    918 2011-03-29 09:03 Faenza/apps/16/Thunar.png