How to specify a higher ruby version for installing a gem

gemrubysoftware installation

I install a ruby package.

$ sudo gem install pdfbeads
ERROR:  Error installing pdfbeads:
    nokogiri requires Ruby version >= 1.9.2.

says that it needs ruby version greater than 1.9.1.

My ruby is 1.8.7.

$ which ruby
/usr/bin/ruby
$ ruby --version
ruby 1.8.7 (2011-06-30 patchlevel 352) [i686-linux]
$ gem --version
1.8.15

I have ruby 1.9.1 and 1.9.3. 

$ whereis ruby1.9.1
ruby1.9: /usr/bin/ruby1.9.1 /usr/bin/ruby1.9.3 /usr/bin/X11/ruby1.9.1 /usr/bin/X11/ruby1.9.3

but 1.9.3 is linked to 1.9.1.

$ ls /usr/bin/ruby* -l
lrwxrwxrwx 1 root root   22 Jul 10 02:33 /usr/bin/ruby -> /etc/alternatives/ruby
-rwxr-xr-x 1 root root 5504 Nov 26  2013 /usr/bin/ruby1.8
-rwxr-xr-x 1 root root 5552 Nov 26  2013 /usr/bin/ruby1.9.1
lrwxrwxrwx 1 root root    9 Nov 26  2013 /usr/bin/ruby1.9.3 -> ruby1.9.1

It says itself is 1.9.3 however:

$  /usr/bin/ruby1.9.3 --version
ruby 1.9.3p0 (2011-10-30 revision 33570) [i686-linux]

I change the link to ruby1.9.3 anyway

$ ls -l /usr/bin/ruby*
lrwxrwxrwx 1 root root    9 Aug 20 21:16 /usr/bin/ruby -> ruby1.9.3
-rwxr-xr-x 1 root root 5504 Nov 26  2013 /usr/bin/ruby1.8
-rwxr-xr-x 1 root root 5552 Nov 26  2013 /usr/bin/ruby1.9.1
lrwxrwxrwx 1 root root    9 Nov 26  2013 /usr/bin/ruby1.9.3 -> ruby1.9.1

The installation still says it needs ruby >= 1.9.2

$ sudo gem install pdfbeads
ERROR:  Error installing pdfbeads:
    nokogiri requires Ruby version >= 1.9.2.
$ gem --version
1.8.15
$ ruby --version
ruby 1.9.3p0 (2011-10-30 revision 33570) [i686-linux]

Do I have ruby1.9.3 or just ruby1.9.1?

How can I make sudo gem install pdfbeads use ruby 1.9.3?

Update:

I have now followed the way of installing ruby 2.1.0 by RVM,
I have added the path of rvm to my PATH.
I then successfully installed ruby2.1.0 by

$ rvm install 2.1.0

and made it default

$ rvm use 2.1.0

$ ruby -v
ruby 2.1.0p0 (2013-12-25 revision 44422) [i686-linux]
$ which ruby
/home/tim/.rvm/rubies/ruby-2.1.0/bin/ruby

Now back to install the package pdfbeads, but without sudo (because I thought I had installed ruby 2.1.0 under my account, not under root, and installation of the package requires the newer version ruby)

$ gem install pdfbeads
ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions into the /var/lib/gems/1.8 directory.

So I think I have to use sudo. But I still get the original error, 

$ sudo gem install pdfbeads

ERROR:  Error installing pdfbeads:
    nokogiri requires Ruby version >= 1.9.2.

I think it is because under sudo, the user is root, which still has the older version ruby1.8.7 as the default. So I wonder what can I do now?

Best Answer

You may wish to consider using a ruby package manager like rvm or rbenv

You can install different rubies and switch between them easily.

You might also want to consider trying 2.0+

Sample output from rvm:

21:59:48 durrantm Castle2012 /home/durrantm 
$ rvm list

rvm rubies

   ruby-1.8.7-p374 [ x86_64 ]
   ruby-1.9.3-p125 [ x86_64 ]
   ruby-1.9.3-p194 [ x86_64 ]
   ruby-1.9.3-p448 [ x86_64 ]
   ruby-2.0.0-p195 [ x86_64 ]
=* ruby-2.0.0-p247 [ x86_64 ]
   ruby-2.0.0-p481 [ x86_64 ]
   ruby-2.1.1 [ x86_64 ]
   ruby-2.1.2 [ x86_64 ]

# => - current
# =* - current && default
#  * - default

21:59:50 durrantm Castle2012 /home/durrantm 
$ rvm use 2.0.0
Using /home/durrantm/.rvm/gems/ruby-2.0.0-p481

$ rvm use 2.1.1
Using /home/durrantm/.rvm/gems/ruby-2.1.1

$ rvm use 1.9.3
ruby-1.9.3-p547 is not installed.

$ rvm use 1.9.3-p448
Using /home/durrantm/.rvm/gems/ruby-1.9.3-p448

Get rvm at http://rvm.io/

Install with its famous 1 liner:

$ \curl -sSL https://get.rvm.io | bash -s stable

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