yum中$releasever、 $basearch等变量含义

以下摘自stackoverflow：

Most distro uses the distroverpkg version to get the releasever and basearch.

If you look at /etc/yum.conf, you will see that distrover is set to redhat-release (for RHEL), enterpriselinux-release (for OEL), and others.

To get the package name:

distro=$(sed -n 's/^distroverpkg=//p' /etc/yum.conf)

To get the releasever:

releasever=$(rpm -q --qf "%{version}" -f /etc/$distro)

To get the basearch:

basearch=$(rpm -q --qf "%{arch}" -f /etc/$distro)

The new code above will try to get the package associated with a file /etc/$distro. Some Linux adds /etc/redhat-release to their package release.

If you get file not owned by any package then use the /etc/*-release file that came with your distro. It is probably /etc/centos-release.

You can check the appropriate /etc/*-release appropriate for this code by checking which file is packaged with centos.

rpm -qf /etc/*-release

Then use this file instead of the first line above.

distro=/etc/centos-release

Here's an example from OEL where /etc/redhat-release is packaged as enterprise-release.

rpm -q --qf "%{name}" -f /etc/redhat-release

总结：

$releasever是取自distro的软件包比如，cent7.2是取centos-release-7-2.1511.el7.centos.2.10.x86_64的version字段；

$basearch是取centos-release-7-2.1511.el7.centos.2.10.x86_64的arch字段。