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Fixing ‘mkmf’ load error Ruby in Ubuntu

If you’re a Debian or Ubuntu user you’ll find that the Ruby standard

distribution is split into lots of little packages so doing something like

apt-get install ruby

only gives you the ruby binary and a subset of the libraries for Ruby. You’ll

need to add more packages if you want to utilize more of Ruby’s standard

library. This is all in order to comply with

Debian packaging Guidelines.

That is all well and good but a little frustrating when you ‘just want to

do work’.

For example, I wanted to install


(Something I really believe should be in Ruby’s standard distribution)

however ran into the following:

$ sudo gem install sys-proctable

Building native extensions. This could take a while…

extconf.rb:8:in `require’: no such file to load — mkmf (LoadError)

    from extconf.rb:8

ERROR: While executing gem … (RuntimeError)

   ERROR: Failed to build gem native extension.

Gem files will remain installed in /usr/lib/ruby/gems/1.8/gems/sys-proctable-0.7.3 for inspection.

To get around this you will need to install ruby1.8-dev (or ruby1.6-dev or

whatever version of ruby you’re running) to get mkmf.rb which is listed

in the Ruby Standard Library.

I’m sure most Ruby hackers worth their salt consider this a ‘duh’ thing

but not of all of us can be shining stars in the Ruby community

How I fixed it…

$ sudo apt-get install ruby1.8-dev


$ sudo gem install sys-proctable

Need to update 4 gems from



Building native extensions. This could take a while…

ruby extconf.rb install sys-proctable

checking for rb_pid_t… yes

creating Makefile


gcc -fPIC -Wall -g -O2 -fPIC -I. -I/usr/lib/ruby/1.8/i486-linux -I/usr/lib/ruby/1.8/i486-linux -I. -DHAVE_TYPE_RB_PID_T -c proctable.c

gcc -shared -L”/usr/lib” -o proctable.o -lruby1.8 -lpthread -ldl -lcrypt -lm -lc

make install

mkdir -p /usr/lib/ruby/gems/1.8/gems/sys-proctable-0.7.3/lib/sys

/usr/bin/install -c -m 0755 /usr/lib/ruby/gems/1.8/gems/sys-proctable-0.7.3/lib/sys

make clean

Successfully installed sys-proctable-0.7.3

Installing ri documentation for sys-proctable-0.7.3…

Installing RDoc documentation for sys-proctable-0.7.3…

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