Hpricot won't install on Ubuntu and complains because mkmf.r

I have mechanize installed on Feisty, which has Ruby 1.8.5, but when I
just tried to install it on Gutsy, which has 1.8.6, I got the following:

root@joehill:~# gem install mechanize
Install required dependency hpricot? [Yn]
Select which gem to install for your platform (i486-linux)

  1. hpricot 0.6 (mswin32)
  2. hpricot 0.6 (jruby)
  3. hpricot 0.6 (ruby)
  4. hpricot 0.5 (ruby)
  5. hpricot 0.5 (mswin32)
  6. Skip this gem
  7. Cancel installation

3
Building native extensions. This could take a while…
ERROR: While executing gem … (Gem::Installer::ExtensionBuildError)
ERROR: Failed to build gem native extension.

ruby extconf.rb install mechanize
extconf.rb:1:in `require’: no such file to load – mkmf (LoadError)
from extconf.rb:1

Gem files will remain installed in
/usr/lib/ruby/gems/1.8/gems/hpricot-0.6 for inspection.
Results logged to
/usr/lib/ruby/gems/1.8/gems/hpricot-0.6/ext/hpricot_scan/gem_make.out
root@joehill:~#
—snip—
If this is a problem with the Ruby install on Gutsy/Ubuntu, please
explain that so I can bug it on Launchpad. Thanks.

xc

You need the ruby development package (ruby1.8-dev).

Jason

Jason R. wrote:

You need the ruby development package (ruby1.8-dev).

Thank you. That fixed it.

On 6 Jul., 21:20, Xeno C. [email protected] wrote:


Building native extensions. This could take a while…
ERROR: While executing gem … (Gem::Installer::ExtensionBuildError)
ERROR: Failed to build gem native extension.

ruby extconf.rb install mechanize
extconf.rb:1:in `require’: no such file to load – mkmf (LoadError)
from extconf.rb:1

I got a similar error when I tried to install mongreal with

gem install mongrel

In another tutorial I found the advice to download the ruby sources

apt-get install ruby1.8-dev build-essential

After I did that I had no problems to install mongreal.
Maybe you have the same problem?

Martin

[email protected] wrote:

On 6 Jul., 21:20, Xeno C. [email protected] wrote:

I think the resolution was installing ruby1.8-dev:

xeno@radioflyer:~$ apt-cache policy ruby1.8-dev
ruby1.8-dev:
Installed: 1.8.5-4ubuntu2
Candidate: 1.8.5-4ubuntu2
Version table:
*** 1.8.5-4ubuntu2 0
500 http://archive.ubuntu.com feisty/main Packages
100 /var/lib/dpkg/status
xc