gem install ultraviolet
Building native extensions. This could take a while...
ERROR: Error installing ultraviolet:
ERROR: Failed to build gem native extension.
/usr/local/rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb
checking for main() in -lonig... no
creating Makefile
make
gcc -I. -I/usr/local/rvm/rubies/ruby-1.9.2-p180/include/ruby-1.9.1/i686-linux -I/usr/local/rvm/rubies/ruby-1.9.2-p180/include/ruby-1.9.1/ruby/backward -I/usr/local/rvm/rubies/ruby-1.9.2-p180/include/ruby-1.9.1 -I. -D_FILE_OFFSET_BITS=64 -fPIC -Wall -o oregexp.o -c oregexp.c
oregexp.c:2:23: fatal error: oniguruma.h: No such file or directory
compilation terminated.
make: *** [oregexp.o] Error 1
Gem files will remain installed in /usr/local/rvm/gems/ruby-1.9.2-p180/gems/oniguruma-1.1.0 for inspection.
Results logged to /usr/local/rvm/gems/ruby-1.9.2-p180/gems/oniguruma-1.1.0/ext/gem_make.out