Most users of Debian/Ubuntu have at some time seen these annoying messages:

<br /> perl: warning: Setting locale failed.<br /> perl: warning: Please check that your locale settings:<br /> LANGUAGE = (unset),<br /> LC_ALL = (unset),<br /> LC_CTYPE = "UTF-8",<br /> LANG = "en_GB.UTF-8"<br /> are supported and installed on your system.<br /> perl: warning: Falling back to the standard locale ("C").<br />

There are a variety of causes – usually locales not being generated properly or incorrect environment variables.

Lately I’ve been getting these a lot of these, but only some of the time. After some messing around I eventually discovered the problem wasn’t on the server itself. The problem only occurs when I’m logged in over SSH from a Mac. The default sshd on Debian copies LANG and LC_ variables* from the client. The LC_CTYPE variable was set on my Mac, apparently by default, to “UTF-8”. While this seems to work on MacOS X, it’s not a valid value for Linux.

The easiest solution was just to add the following to my ~/.profile on the Mac:

<br /> export LC_CTYPE=en_GB.UTF-8<br />

That fixes it, and doesn’t appear to cause harm on the Mac.