[Forwarding bug https://bugs.gentoo.org/680244 as requested by the
Gentoo package maintainer.]
According to printf(1):
Interpreted sequences are:
[...]
\uHHHH Unicode (ISO/IEC 10646) character with hex value HHHH (4 digits)
\UHHHHHHHH
Unicode character with hex value HHHHHHHH (8 digits)
It does not work, though:
$ /usr/bin/printf '\u0041\n'
/usr/bin/printf: invalid universal character name \u0041
$ /usr/bin/printf '\U00000041\n'
/usr/bin/printf: invalid universal character name \U00000041
Other tools interpret the sequence correctly:
$ printf '\u0041\n' # bash
A
$ echo -e '\u0041' # bash
A
$ zsh -c "echo -e '\u0041'"
A
$ emacs -Q --batch --eval '(princ "\u0041\n")'
A
$ python -c "print ('\u0041')"
A
$ ruby -e 'print("\u0041\n")'
A
