I'm guessing you're an American, because everybody else is very ill served by the C/POSIX locale. Locales are about something different than general text mungi

I'm guessing you're an American, because everybody else is very ill served by the C/POSIX locale. Locales are about something different than general text munging, and if setting the locale to something other than C (which, BTW, is done by default on Ubuntu since many years ago; been en_US.UTF-8 since as far back as I can remember) broke software, that software is seriously stupidly designed. Locales are about making the date come out in the order the user was expecting, the default text encoding, error messages. They are fundamentally about interfacing to the user in the way that the user expects. And yes, they are flawed, seriously so, mostly due to a lack of ambition. setlocale assumes that the locale the user is currently working in is also the locale the user has always been working in since time immemorial, and it assumes there is only one user. If you have a multilingual document, you're in trouble. If you use the locale date/time printer for anything other than immediate input and output to the user, you're in trouble (and there are circles of hell that certain Usenet newsreader authors will burn in for all eternity for this one). Any time you write a file out to disk with one locale and read it in with another you are potentially in horrible danger. This is where something like ICU comes in really handy; any time you have to deal with data from several different origins, you will be ill served by locale. So in that sense, you're quite right. But all this is a very different problem from making printf work the way it is advertised as doing, from making it possible to output a Unicode string that you have told the computer in as many ways that you wish to output in UTF-8, write in UTF-8. If you want to do simple text output and not deal with ICU, GNU recode, whatever, you need to use setlocale or your libc will mutely suppress everything but 7-bit ASCII, and you will be very, very confused.