Thank you for you answer, but your example not work for me...
Please try to the following if you can choose a font.
options(X11fonts=c("-cronyx-helvetica-%s-%s-*--%d-*-*-*-*-*-*-*",
+
"-adobe-symbol-medium-r-*-*-%d-*-*-*-*-*-*-*"))
plot(1:20,main="russian string.")
I not specialist in locales and fonts, maybe reason in my locale?
In my linux locale is UTF-8:
LANG=ru_RU.UTF-8
LC_CTYPE="ru_RU.UTF-8"
LC_NUMERIC="ru_RU.UTF-8"
LC_TIME="ru_RU.UTF-8"
LC_COLLATE="ru_RU.UTF-8"
LC_MONETARY="ru_RU.UTF-8"
LC_MESSAGES="ru_RU.UTF-8"
LC_PAPER="ru_RU.UTF-8"
LC_NAME="ru_RU.UTF-8"
LC_ADDRESS="ru_RU.UTF-8"
LC_TELEPHONE="ru_RU.UTF-8"
LC_MEASUREMENT="ru_RU.UTF-8"
LC_IDENTIFICATION="ru_RU.UTF-8"
LC_ALL=
,but fonts in xfontsel is koi8-r(in rgstry)