LMDE2 / MATE locale charset inconsistency

Question

I have a machine with Linux Mint Debian Edition 2 "Betsy" (installed as RC, with all available updates applied) and MATE desktop environment. My problem is that in some applications special characters used in my mother tongue (Polish) and, as I have some folders and files containing are not handled correctly.

To be more specific: in mate-terminal, pluma (MATE text editor) and caja (file manager) and probably a few others I just didn't happen to check, any Polish special characters normally typed by Alt+letter are either ignored (no character printed -- in pluma and caja) or replaced with a question mark (in mate-terminal). Even vim, when run in mate-terminal, behaves this way, i.e. replaces special characters with question marks.

I don't think this is a system-wide problem. Why? Because when I switch to another tty and try to input those special characters in the terminal I encounter no problems. The same folder which by mate-terminal is displayed as zdj?cia in another tty is correctly labeled zdjęcia. It looks as though the problem is MATE-specific, since vim, when run in terminator, doesn't cause any problems.

Furthermore, I've tried debugging this in the following manner: in mate-terminal I listed my home directory (containing files and directories with Polish special characters) and redirected ls output to a test file. Then I switched to another tty and cat the test file -- the characters were printed correctly.

I've already tried dpkg-reconfigure locales. Language packs have been installed (and reinstalled in the process) via MATE Control Centre.

What do I try next?

EDIT:

In mate-terminal in graphical environment:

$ locale
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG=en_GB.UTF-8
LANGUAGE=
LC_CTYPE="en_GB.UTF-8"
LC_NUMERIC=\"pl_PL.UTF-8\"
LC_TIME=en_GB.UTF-8
LC_COLLATE="en_GB.UTF-8"
LC_MONETARY=\"pl_PL.UTF-8\"
LC_MESSAGES="en_GB.UTF-8"
LC_PAPER=\"pl_PL.UTF-8\"
LC_NAME=\"pl_PL.UTF-8\"
LC_ADDRESS=\"pl_PL.UTF-8\"
LC_TELEPHONE=\"pl_PL.UTF-8\"
LC_MEASUREMENT=\"pl_PL.UTF-8\"
LC_IDENTIFICATION=\"pl_PL.UTF-8\"
LC_ALL=

In tty1 (where character encoding works fine):

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

EDIT:

grep -Rs pl_PL /etc ~/.?* yields, after removing "Binary file x matches pattern" and piping through sort | uniq:

/etc/default/locale
/etc/locale.alias
/etc/locale.gen
/etc/mdm/locale.conf
/home/marta/../marta/.bash_history
/home/marta/../marta/.config/user-dirs.locale
/home/marta/../marta/.linuxmint/mintMenu/apt.cache
/home/marta/../marta/.pam_environment
/home/marta/../marta/.xsession-errors
/home/marta/.bash_history
/home/marta/.config/user-dirs.locale
/home/marta/.linuxmint/mintMenu/apt.cache
/home/marta/.pam_environment
/home/marta/.xsession-errors

Yes, the computer's not actually mine, but never mind :)

Yet another EDIT:

The contents of files containing locale settings:

$ cat /etc/default/locale
LANG="en_GB.UTF-8"
LANGUAGE="en_GB:en"
LC_NUMERIC="pl_PL.UTF-8"
LC_TIME="en_GB.UTF-8"
LC_MONETARY="pl_PL.UTF-8"
LC_PAPER="pl_PL.UTF-8"
LC_IDENTIFICATION="pl_PL.UTF-8"
LC_NAME="pl_PL.UTF-8"
LC_ADDRESS="pl_PL.UTF-8"
LC_TELEPHONE="pl_PL.UTF-8"
LC_MEASUREMENT="pl_PL.UTF-8"

$ cat /home/marta/.pam_environment
LC_NUMERIC="pl_PL.UTF-8"
LC_TIME=en_GB.UTF-8
LC_MONETARY="pl_PL.UTF-8"
LC_PAPER="pl_PL.UTF-8"
LC_IDENTIFICATION="pl_PL.UTF-8"
LC_NAME="pl_PL.UTF-8"
LC_ADDRESS="pl_PL.UTF-8"
LC_TELEPHONE="pl_PL.UTF-8"
LC_MEASUREMENT="pl_PL.UTF-8"

$ cat /home/marta/.config/user-dirs.locale
pl_PL

Answer 1

You probably have a .pam_environment file with double quotes around the values of the LC_ variables:

# WRONG
LC_TIME="en_US.UTF-8"

Instead, it should look like this (no quotes):

LC_TIME=en_US.UTF-8

So, either remove your .pam_environment file

mv ~/.pam_environment ~/.pam_environment.off

or edit it to remove the double-quotes around the values:

perl -i.bak -pe 's/"//g' ~/.pam_environment

For details, see this : "Generated locale files must not have double quotes" on Github in linuxmint/mintlocale