Linux has a stty setting iutf8. This is necessary for utf-8 locales for the following reason:
When you enter a non-us-ascii utf-8 character in canonical mode (for example, when cat > file is run on the shell command line) it will be two or more bytes long. If you now hit the erase key (ie., backspace) only one byte will be deleted from the input buffer. For example, if you input äü and hit backspace, the input buffer will now contain two bytes of utf-8 code for ä and the first byte of the utf-8 code for ü, for a total of three bytes, which are invalid.
The iutf8 flag tells the terminal that the input is in utf8 and that the erase key in canonical mode should erase all bytes of the rightmost character.
FreeBSD should support iutf8 so that canonical mode works fine with utf8 locales.
(In reply to Peter Backes from comment #0)
What is the current status of the problem?