reverting yum back to fc6

[Mike Cohler]

Kahn Seidl <mkseidl <at> hotmail.com> writes:

> so I tried to upgrade to fedora 7 via yum.  But it failed.  But now I want

It would seem that a lot of people have problems when upgrading via yum from
one version of Fedora to the next. Rather than upgrade it is likely to lead
to less problems overall if you do a clean install - but then you will say
"but what about all my previous setups and user files!"

The most likely install method to result in as few problems as possible when
a new version is released is to do a clean install - though your
mileage may vary!

However I have not seen a writeup of the way I do it which preserves what
you had in the old system as much as possible, and gets you up and running
with relatively minimal pain.

What I do is as follows:

Firstly I have a separate partition for /opt and a subpartition within this
for home.  The root partition (/) is on its own. On some machines I have
/opt and /home as two separate disc partitions. In principle then once you
are running with a working version of Fedora there is then no need to
overwrite the /opt and /home partitions if you install a new version into
the separate root partition.

So when doing an upgrade I prepare for it by recording which partitions
have which bits in, and also make copies (say using rsync) of the /etc /var
and /root directories so that there are copies of key files for networking,
bind, mail etc which can be copied to the new system. This is really vital!

In addition keeping a record which which extra packages were in the system
from livna, extras etc is useful so that I can install these immediately
after the new install.

Then a fresh clean install for the new system is begun, and when reaching
disc partitioning I do not select the default but do a custom disc
partitioning. What I do is to select the root partition, and ask it to
format this area before installing, and to select the other partitions
for /opt and/or /home putting the mount points back, but NOT formatting
these partitions.
This was /opt and /home are not touched during the install, and keep all
the previous user data.

Then proceed with the rest of the install, selecting packages as I need for
the system (and for F7 making sure that I do NOT install tclhtttp as
it will create a user with UID 500 which will likely conflict with UIDs
of users already in existence on the /home partition.

Once the install is complete, do NOT create any new users - just root.

After firstboot, login as root and if there is a home directory as a
sub-directory of /opt ( say as /opt/home then cd to / and move the
existing home directory out of the way by say "mv home home.DIST"
and then link the mount point using "ln -s /opt/home ."
Now /home contains the links to the previous users.

Now it is necessary to bring back the user data for all the users, so go
into /etc and edit the "passwd" and "group" files to append line ( one
line for each user) from the same files that  you had saved from the
previous running version. See above!

Then change permissions for shadow and group temporarily to 600 and edit
these two files to append the lines for each user from the shadow and
gshadow files from the previous system, that you had saved. Then change
permissions back
to 400. Now the user information, and all their passwords are as they
were in the old system - this is important.

All the user files and login setup should now have been preserved and
at this point it should be possible to login to any of the previous
users though a few settings may need to be tweaked once a user is
logged in- eg the clock settings may have changed in KDE.

Now copy back from the saved versions the files /etc/resolv.conf
/etc/hosts /etc/sysconfig/network
/etc/sysconfig/network-scripts/ifcfg-eth0 and related
files.  Also any changes to /etc/aliases /etc/mail/mailertable and
/etc/mail/local-host-names

Bring back any "named" i.e. (bind setup) related files from your saved
copies.

Restart the system and at this point you should be up and running
with the network available and be able to log in as any of the
users for the previous system but now using the new
operating system.

It is wise at this point to then do a yum update to bring in known
updates to packages, and then yum install any missing packages that
you had on the previous system.

With this basic technique it is possible to go from FC6 to an up to
date F7 leaving all the previous user files untouched in
about 3 hours.
This is what I did on one machine yesterday afternoon.
For a machine using wired ethernet this rarely goes wrong
unless the install itself fails. For wireless networked machines
there may be new things in the wireless packages that
need to be fixed and since wireless for ipw3945 is very new
this is ongoing work. However ipw2200 is straightforward.
Wireless in general may need drivers setting up.

Hope this helps.

-- 

mike cohler