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user@sv1 [/home/user/]# env|grep GEM
GEM_HOME=/home/user/.gems/2.1
GEM_PATH=/home/user/.gems/2.1

user@sv1 [/home/user/]# gem install mysql2
Building native extensions.  This could take a while...
Successfully installed mysql2-0.3.18
1 gem installed

that installs mysql2.so in multiple locations:
user@sv1 [/home/user/]# find /home/user/.gems -name mysql2.so
/home/user/.gems/2.1/extensions/x86_64-linux/2.1.0-static/mysql2-0.3.18/mysql2/mysql2.so
/home/user/.gems/2.1/gems/mysql2-0.3.18/ext/mysql2/mysql2.so
/home/user/.gems/2.1/gems/mysql2-0.3.18/lib/mysql2/mysql2.so

user@sv1 [/home/user/]# ls -l /home/user/.gems/2.1/extensions/x86_64-linux/2.1.0-static/mysql2-0.3.18/mysql2/mysql2.so
-rwxr-xr-x 1 user user 64842 mar 18 16:13 /home/user/.gems/2.1/extensions/x86_64-linux/2.1.0-static/mysql2-0.3.18/mysql2/mysql2.so
user@sv1 [/home/user/]# ls -l /home/user/.gems/2.1/gems/mysql2-0.3.18/ext/mysql2/mysql2.so
-rwxr-xr-x 1 user user 64842 mar 18 16:13 /home/user/.gems/2.1/gems/mysql2-0.3.18/ext/mysql2/mysql2.so

now I want to rebuild this extension so I do:
user@sv1 [/home/user/]# gem install mysql2
Building native extensions.  This could take a while...
Successfully installed mysql2-0.3.18
1 gem installed

user@sv1 [/home/user/]# ls -l /home/user/.gems/2.1/extensions/x86_64-linux/2.1.0-static/mysql2-0.3.18/mysql2/mysql2.so
-rwxr-xr-x 1 user user 64842 mar 18 16:13 /home/user/.gems/2.1/extensions/x86_64-linux/2.1.0-static/mysql2-0.3.18/mysql2/mysql2.so
user@sv1 [/home/user/]# ls -l /home/user/.gems/2.1/gems/mysql2-0.3.18/ext/mysql2/mysql2.so
-rwxr-xr-x 1 user user 87485 mar 18 16:16 /home/user/.gems/2.1/gems/mysql2-0.3.18/ext/mysql2/mysql2.so

as you can see /home/user/.gems/2.1/extensions/x86_64-linux/2.1.0-static/mysql2-0.3.18/mysql2/mysql2.so was not rebuild. what is worse this file actualy is used when "require 'mysql2'" in ruby code. This blocks rebuilding/updateing a gem. Of course I can solve it by removing this old file and "gem install" then but this causes a lot of new variables to remember and a lot of hard to diagnose problems. How do i rebuild all files of the gem (mysql2.so here) with a gem command? Or maybe its a bug in a "gem" program?

This problem is not specific to mysql2 gem as other gems are behaving same way.

One might say that its not necessary to rebuild a gem when its version did not change - but it is when libs that its linked to was updated/changed (for example libmysqlclient for mysql2 gem)

mhi
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1 Answers1

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You may be looking for the pristine option:

gem pristine mysql -v 0.3.18

or without the -v I believe it will just work on the most recent version but there is also the --all option.

See gem help pristine for documentation:

Restores installed gems to pristine condition from files located in the gem
cache

Using pristine also includes rebuilding any gem extensions which will re-link the binaries with the current libs.

Peter Giacomo Lombardo
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