Can (GNU) find perform accent-insensitive (diacritic-insensitive) searches?

Question

I would like to perform an accent-insensitive search for files in a directory hierarchy.

$ touch a ą ä à á â
$ find . -iname '*a*'
./a
# How do I get find to return all 6 filenames?

I'm running Debian 11, Bullseye

My collation-fu is very weak!

Is there an option, locale setting, or some other method that I could use to make find work in an accent-insensitive manner?

As requested in a comment, locale returns:

LANG=en_GB.UTF-8
LANGUAGE=en_GB:en
LC_CTYPE="en_GB.UTF-8"
LC_NUMERIC="en_GB.UTF-8"
LC_TIME="en_GB.UTF-8"
LC_COLLATE="en_GB.UTF-8"
LC_MONETARY="en_GB.UTF-8"
LC_MESSAGES="en_GB.UTF-8"
LC_PAPER="en_GB.UTF-8"
LC_NAME="en_GB.UTF-8"
LC_ADDRESS="en_GB.UTF-8"
LC_TELEPHONE="en_GB.UTF-8"
LC_MEASUREMENT="en_GB.UTF-8"
LC_IDENTIFICATION="en_GB.UTF-8"
LC_ALL=

Answer 1

TL;DR Scroll to the end

That's a fantastic question. Thanks for asking it.

It is possible to perform an accent-insensitive search, but not by default, and not automatically, as far as I know. You can find all six of your sample files with this:

find . -name '[[=a=]]'

That's standard POSIX glob notation for all-characters-that-are-like-a-but-maybe-with-an-accent.

So, if you know all of the characters that might have an accented version, you can use the above notation explicitly in your searches. e.g.:

find . -name 'fran[[=c=]]ais' # To match a cedilla

But that's tedious and deeply unsatisfactory.

Note that the [[=a=]] notation can also be used with characters for which there aren't any accented versions. So [[=k=]] will match k.

So I recommend creating a script (accented) that takes a string on the command line, replaces every letter with the [[=x=]] version of it, and prints out the result, and then you can use that with find. e.g.:

#!/usr/bin/env perl
print join('', map { /\p{Letter}/ ? "[[=$_=]]" : $_ } split //, $ARGV[0]), "\n";

Using that with find might look like:

find . -name "`accented a`"

If you want it to feel automatic, and if you only use find in the most simple way, you could create a shell script (ffind) that combines find and accented:

#!/bin/sh
find "$1" -name "`accented \"$2\"`"

Then you could do:

ffind . a

But that would make it impossible to use find's other predicates.

When you need that, you would have to use the real find and accented explicitly (like above).

Here

A smarter solution is a wrapper around find (ffind) that scans for -name and -iname arguments, and effectively applies accented to the following argument, and then executes the resulting modified find command. e.g.:

#!/usr/bin/env perl
use warnings;
use strict;
# ffind - find wrapper that makes -name and -iname accent-insensitive
my @cmd;
while (@ARGV)
{
    # Gather command line arguments
    push @cmd, shift @ARGV;

    # Make -name and -iname arguments accent-insensitive
    if ($cmd[-1] =~ /^-i?name$/ && @ARGV)
    {
        push @cmd, join('', map { /\p{Letter}/ ? "[[=$_=]]" : $_ } split //, shift @ARGV);
    }
}
exec 'find', @cmd;

Then you can do to this to find all six of your sample files:

ffind . -name a

Of course, you could call it find and change the 'find' on the last line to '/usr/bin/find', and that would make find accent-insensitive transparently:

find . -name a

Sadly, this entire approach only works on some systems, like Debian 12, but not all. :-(

Answer 2

You could transform the names to a decomposed form, remove combining marks and check against that:

find . -print0 |
  perl -C -MUnicode::Normalize -MFile::Basename -0 -lne '
    $name = NFD(basename($_)) =~ s/\pM//r;
    print if $name =~ /a/' |
  xargs -r0 ls -ld --