Upgrading Red Hat Enterprise Linux / CentOS / Oracle Linux
RHEL/CentOS/Oracle Linux Migration
Package Management with rpm and yum/dnf
Building Software From Source
There have been only minor changes in software package management and the task of building software from source. The biggest change hasn't been within Linux itself, but has been the Internet locations of the major free software archives.
Previous: StorageThe previous page explained how storage has changed as the default file system type has migrated from Ext3 to Ext4 to XFS and possibly to Btrfs depending on the distribution.
6 — Package Management
RHEL 5.* gave you both IA32 and IA64 binaries and libraries for most packages when you install onto 64-bit hardware. Put another way, starting with RHEL 6 you no longer get two lines of output when you type:
$ rpm -q firefox
and so you no longer have to type this to figure it out:
$ rpm -q --qf '%{name}.%{arch}\n' firefox
Package Management
See my page on
package management
for details on rpm and yum,
as well as other Linux package systems like the Debian
and Ubuntu apt-get and dpkg
and the Mageia urpm system,
plus OpenBSD and Solaris package management.
BaseOS versus AppStream
With RHEL 8, the packages are split into BaseOS versus AppStream. On the DVD image they are top-level directories, each with subdirectories Packages and repodata, so they function as two separate package repositories.
yum versus dnf
The dnf program has replaced yum,
but you won't notice the difference!
With RHEL 8, /usr/bin/yum
is a symbolic link to dnf-3.
The command syntax, and result of using the command,
remains the same.
The upgrade from yum to dnf
replaced the "engine" that works out the dependencies.
The new version should run much faster while giving
the same results.
7 — Building Software from Source
Starting with RHEL 6,
rpmbuild and related tools no longer use
directories under /usr/src/ as their
working area.
They instead use ~/rpmbuild,
meaning that things like building a kernel as root
requires an unusually large amount of space on the /
partition.
That is, unless you do this:
# mkdir /usr/src/rpmbuild # ln -s /usr/src/rpmbuild ~/rpmbuild
For reasons completely unrelated to any specific Linux distribution, the standard free software web sites have changed. Formerly useful sites like sourceforge.net, freshmeat.net, freecode.com, and freshrpms.net have been replaced by GitHub and, to a limited extent, RPM Fusion. Although, somewhat useful versions of Sourceforge and Freecode may be back...
The next section is on networking, an area that really changed between RHEL 6 and 7.