alessio@alessio-Extensa-5510:~  
→ rvm install jruby
jruby-1.6.3 - #fetching 
jruby-1.6.3 - #extracted to /home/alessio/.rvm/src/jruby-1.6.3 (already extracted)
Building Nailgun
jruby-1.6.3 - #installing to /home/alessio/.rvm/rubies/jruby-1.6.3
jruby-1.6.3 - #importing default gemsets (/home/alessio/.rvm/gemsets/)
Copying across included gems
Building native extensions.  This could take a while...
ERROR:  Error installing jruby-launcher:
	ERROR: Failed to build gem native extension.

        /home/alessio/.rvm/rubies/jruby-1.6.3/bin/jruby extconf.rb

make
make -f inc/Makefile-rules.mk CONF=unix SUBPROJECTS= .build-conf
make[1]: Entering directory `/home/alessio/.rvm/gems/jruby-1.6.3/gems/jruby-launcher-1.0.8-java'
make -f inc/Makefile-rules.mk jruby
make[2]: Entering directory `/home/alessio/.rvm/gems/jruby-1.6.3/gems/jruby-launcher-1.0.8-java'
mkdir -p build/unix/Linux
rm -f build/unix/Linux/argparser.o.d
g++ -O2 -Wall    -c argparser.cpp -MMD -MP -MF build/unix/Linux/argparser.o.d -o build/unix/Linux/argparser.o
argparser.cpp: In member function ‘bool ArgParser::initPlatformDir()’:
argparser.cpp:162:58: warning: ignoring return value of ‘char* getcwd(char*, size_t)’, declared with attribute warn_unused_result
mkdir -p build/unix/Linux
rm -f build/unix/Linux/utilsfuncs.o.d
g++ -O2 -Wall    -c utilsfuncs.cpp -MMD -MP -MF build/unix/Linux/utilsfuncs.o.d -o build/unix/Linux/utilsfuncs.o
mkdir -p build/unix/Linux
rm -f build/unix/Linux/ng.o.d
gcc -O2 -Wall    -c ng.c -MMD -MP -MF build/unix/Linux/ng.o.d -o build/unix/Linux/ng.o
mkdir -p build/unix/Linux
rm -f build/unix/Linux/strlcpy.o.d
gcc -O2 -Wall    -c strlcpy.c -MMD -MP -MF build/unix/Linux/strlcpy.o.d -o build/unix/Linux/strlcpy.o
mkdir -p build/unix/Linux
rm -f build/unix/Linux/jrubyexe.o.d
g++ -O2 -Wall    -c jrubyexe.cpp -MMD -MP -MF build/unix/Linux/jrubyexe.o.d -o build/unix/Linux/jrubyexe.o
mkdir -p build/unix/Linux
rm -f build/unix/Linux/unixlauncher.o.d
g++ -O2 -Wall    -c unixlauncher.cpp -MMD -MP -MF build/unix/Linux/unixlauncher.o.d -o build/unix/Linux/unixlauncher.o
g++ -O2 -Wall     -o build/unix/Linux/jruby-launcher build/unix/Linux/argparser.o build/unix/Linux/utilsfuncs.o build/unix/Linux/ng.o build/unix/Linux/strlcpy.o build/unix/Linux/jrubyexe.o build/unix/Linux/unixlauncher.o -lstdc++
cp build/unix/Linux/jruby-launcher jruby
make[2]: Leaving directory `/home/alessio/.rvm/gems/jruby-1.6.3/gems/jruby-launcher-1.0.8-java'
make[1]: Leaving directory `/home/alessio/.rvm/gems/jruby-1.6.3/gems/jruby-launcher-1.0.8-java'
/home/alessio/.rvm/rubies/jruby-1.6.3/bin/jruby -S rake
(in /home/alessio/.rvm/gems/jruby-1.6.3/gems/jruby-launcher-1.0.8-java)
rspec 2.0.0 or higher is not installed; skipping jruby-launcher specs

make install
cp ./jruby /home/alessio/.rvm/rubies/jruby-1.6.3/bin/jruby
cp: cannot create regular file `/home/alessio/.rvm/rubies/jruby-1.6.3/bin/jruby': Text file busy
make: *** [install] Error 1


Gem files will remain installed in /home/alessio/.rvm/gems/jruby-1.6.3/gems/jruby-launcher-1.0.8-java for inspection.
Results logged to /home/alessio/.rvm/gems/jruby-1.6.3/gems/jruby-launcher-1.0.8-java/./gem_make.out
