I tried to use rgrep to search in cyrillic files with UTF-8 encoding (M-x rgrep command with search query бонус), the resulting command name was

/usr/bin/find . -type d ( -path */SCCS -o -path */RCS -o -path */CVS -o -path */MCVS -o -path */.src -o -path */.svn -o -path */.git -o -path */.hg -o -path */.bzr -o -path */_MTN -o -path */_darcs -o -path */{arch} ) -prune -o ! -type d ( -name .#* -o -name *.o -o -name *\~ -o -name *.bin -o -name *.lbin -o -name *.so -o -name *.a -o -name *.ln -o -name *.blg -o -name *.bbl -o -name *.elc -o -name *.lof -o -name *.glo -o -name *.idx -o -name *.lot -o -name *.fmt -o -name *.tfm -o -name *.class -o -name *.fas -o -name *.lib -o -name *.mem -o -name *.x86f -o -name *.sparcf -o -name *.dfsl -o -name *.pfsl -o -name *.d64fsl -o -name *.p64fsl -o -name *.lx64fsl -o -name *.lx32fsl -o -name *.dx64fsl -o -name *.dx32fsl -o -name *.fx64fsl -o -name *.fx32fsl -o -name *.sx64fsl -o -name *.sx32fsl -o -name *.wx64fsl -o -name *.wx32fsl -o -name *.fasl -o -name *.ufsl -o -name *.fsl -o -name *.dxl -o -name *.lo -o -name *.la -o -name *.gmo -o -name *.mo -o -name *.toc -o -name *.aux -o -name *.cp -o -name *.fn -o -name *.ky -o -name *.pg -o -name *.tp -o -name *.vr -o -name *.cps -o -name *.fns -o -name *.kys -o -name *.pgs -o -name *.tps -o -name *.vrs -o -name *.pyc -o -name *.pyo ) -prune -o -type f ( -iname *.org ) -exec grep --color -i -nH -e \б\о\н\у\с {} +

As you can see the search term was quoted with slashes \б\о\н\у\с, and inspite of -i option to grep the result was case-sensitive, e.g. lines with бонус were found, but Бонус or БОНУС were not. Of course I can use regexp in search query, but I'd like to avoid this for convenience reason.

How to make such a search really case-insensitive?

I use GNU Emacs 25.3.1 (x86_64-unknown-cygwin) of 2017-09-12 (emacs-w32.exe from cygwin installation) on Windows 7. BTW, the same case-sensitive results I get when use grep -i бонус *.org in shell under emacs, while in cygwin shell the result is correct.

UPD: Execution of locale command in emacs shell result in the following:

sh-4.4$ locale

It seems my locale settings are broken...

  • While the question is useful, and I do not know the answer : but this is not an emacs question. Do you see the same behaviour directly running your grep in command line ? Maybe you can try the cygwin command line. Cygwin , windows, or grep experts would be better placed to answer it.
    – Jeeves
    Aug 14, 2018 at 13:20
  • @Jeeves, I believe it is an emacs question, emacs quotes the query.
    – zeliboba
    Aug 14, 2018 at 14:30
  • 1
    @zeliboba it could be an Emacs question. If you tell us if it works fine in cygwin shell, we would know.
    – Jeeves
    Aug 14, 2018 at 17:53

1 Answer 1


The C locale is a backwards-compatible special case for legacy 8-bit systems and looks suspicious here; try set a proper locale like en_us.utf-8. (I don't particularly like or recommend the US part but if that fixes it, we can figure out a better one for you. Maybe try ru.utf-8 too.)

  • A brief explanation about my locale settings: the system locale in windows is set to English (UK), and locale enviroment variables LC_* for cygwin were not set system-wide, they are set in .bash_profile. Emacs was running from shortcut with command line C:\cygwin\bin\run.exe /usr/bin/emacs and therefore it did not pickup these variables and locale for Emacs was not correct. Changing the command line to C:\cygwin\bin\run.exe bash -l -c /usr/bin/emacs solved the problem.
    – zeliboba
    Aug 15, 2018 at 8:28
  • One may need to add --wait option to run.exe in the command above, but this is purely cygwin stuff.
    – zeliboba
    Aug 15, 2018 at 8:53
  • I also encounter similar locale issue on MacOS, just for a reference this issue discussed here emacs.stackexchange.com/questions/10822/…
    – zeliboba
    May 12, 2019 at 10:14
  • The broader question of how to properly set your locale for GUI applications in your OS of choice (or, in the case of Windows, probably unfortunate necessity more than preference) is not Emacs-specific.
    – tripleee
    May 12, 2019 at 11:04

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