xml – 无法在Ubuntu 11.04中安装R包[closed]

我在Ubuntu 11.04中安装了R 2.12。今天我试图安装一个新的包，所以我运行以下命令：

install.packages('XML')

但安装失败，并提供以下信息：

* installing *source* package ‘XML’ ...
checking for gcc... gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables... 
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking how to run the C preprocessor... gcc -E
No ability to remove finalizers on externalptr objects in this verison of R
checking for sed... /bin/sed
checking for pkg-config... /usr/bin/pkg-config
checking for xml2-config... no
Cannot find xml2-config
ERROR: configuration failed for package ‘XML’
* removing ‘/home/spirit/R/i686-pc-linux-gnu-library/2.12/XML’

The downloaded packages are in
    ‘/tmp/RtmpoZYxnv/downloaded_packages’
Warning message:
In install.packages("XML") :
  installation of package 'XML' had non-zero exit status

我也试过：

sudo install.packages('XML')

但它给出相同的错误信息。

任何人都可以给我任何建议吗？提前致谢。