IUS vs. Software Collections


In 2013, Red Hat released a product called Software Collections (RHSCL). This product later got it's own community website. The front page has this statement:

Software Collections give you power to build, install, and use multiple versions of software on the same system, without affecting system-wide installed packages.

Here is our mission statement for the IUS Community project:

IUS is a community project that provides RPM packages for newer versions of select software for Enterprise Linux distributions.

Both projects seek to solve the same problem, but differ greatly in execution.

Types of Packages

File Locations


php -v
service mysqld start
mysql -V
python2.7 -V
scl enable php54 "php -v"
service mysql55-mysqld start
scl enable mysql55 "mysql -V"
scl enable python27 "python -V"



Q. On EL5 I see multiple packages that seem to be related to MySQL 5.5, such as mysql55, mysql55-server, and mysql55-mysql-server. What is the difference?

A. The IUS package for MySQL 5.5 is named mysql55, and it has several subpackages that follow the pattern mysql55-component (mysql55-server, mysql55-libs, etc). While RHSCL is not available for RHEL 5, Red Hat did add their mysql55 SCL to the EL5 base channel. This is a problem because the main SCL metapackage is also named mysql55. The SCL subpackages follow the pattern mysql55-mysql-component (mysql55-mysql-server, mysql55-mysql-libs, etc). We evaluated renaming our mysql55 package to mysql55u to avoid the name conflict with the SCL metapackage, but we were not able to find a solution that provided seamless upgrades. While our current understanding is that the SCL metapackage is optional, it is still an unfortunate conflict with no clear solution. The safest approach to handle this is to add the line exclude=mysql55* to the configuration of the repository you do not want to use. Please refer to the RHEL 5 MySQL 5.5 migration guide for more information.

More Info