How do I fix my locale and language settings?

When logging in to NeSI from some systems, such as Windows Subsystem for Linux, you might get messages like the following while using NeSI (the following message is obtained when running man):

man: can't set the locale; make sure $LC_* and $LANG are correct

To get rid of this message, save a text file called .i18n in your home directory, with the following contents:

LC_ALL="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_CTYPE="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_TIME="en_US.UTF-8"

If you know what you're doing, you can replace each instance of "en_US.UTF-8" with a different locale. You can get a list of available locales by running locale -a. Use a different locale at your own risk, however.