Fehlermeldung:

Building native extensions.  This could take a while...
ERROR:  Error installing garb:
ERROR: Failed to build gem native extension.

/usr/bin/ruby1.8 extconf.rb install garb –no-ri –no-rdoc
checking for socket() in -lsocket… no
checking for gethostbyname() in -lnsl… yes
checking for atan() in -lm… no
checking for atan() in -lm… yes
checking for inflate() in -lz… no
checking for inflate() in -lzlib… no
checking for inflate() in -lzlib1… no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
–with-opt-dir
–without-opt-dir
–with-opt-include
–without-opt-include=${opt-dir}/include
–with-opt-lib
–without-opt-lib=${opt-dir}/lib
–with-make-prog
–without-make-prog
–srcdir=.
–curdir
–ruby=/usr/bin/ruby1.8
–with-iconv-dir
–without-iconv-dir
–with-iconv-include
–without-iconv-include=${iconv-dir}/include
–with-iconv-lib
–without-iconv-lib=${iconv-dir}/lib
–with-zlib-dir
–without-zlib-dir
–with-zlib-include
–without-zlib-include=${zlib-dir}/include
–with-zlib-lib
–without-zlib-lib=${zlib-dir}/lib
–with-socketlib
–without-socketlib
–with-nsllib
–without-nsllib
–with-mlib
–without-mlib
–with-mlib
–without-mlib
–with-zlib
–without-zlib
–with-zliblib
–without-zliblib
–with-zlib1lib
–without-zlib1lib
extconf failure: need zlib

Gem files will remain installed in /usr/lib/ruby/gems/1.8/gems/libxml-ruby-1.1.3 for inspection.
Results logged to /usr/lib/ruby/gems/1.8/gems/libxml-ruby-1.1.3/ext/libxml/gem_make.out

Lösung:

sudo apt-get install libxml-dev
sudo apt-get install libxml
sudo apt-get install libxml2-dev
sudo gem install garb