POSIX requires the '+' flag in %C to output padding with leading 0, and additionally to add a +/- indicator if the minimum field width is larger than 2 bytes. Thus:
date -d 0001-01-01 +.%+4C. should produce ".+000.", but currently it produces ".%+4C." because the + flag is unimplemented. See also http://austingroupbugs.net/view.php?id=1184 -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org