Reinstalling an Older Software Release

The steps below describe the procedure for installing an older IRIX release after you have installed the new release. You should perform a complete system backup before performing this procedure.

In the procedure you will back up your new, modified system configuration files, remove your new system software, and then install an older version. The final step is to integrate any modifications you made to your new configuration files into the restored, older configuration files.

Note: This procedure begins from the miniroot, not from IRIX. Before beginning this procedure you should locate the older software distribution you will be downgrading to. Be sure that you have the installation tools (sa file) that accompanied the older distribution.

1. Load the miniroot from your current distribution.

   Begin by loading the miniroot from your current distribution. (Refer to "Starting a Miniroot Installation" in Chapter 3 for information on how to load the miniroot).

2. Invoke an IRIX shell.

   Use the shroot command to escape to a root shell, enter sh to start a Bourne shell, and then use showfiles to create a list of modified configuration files:

   Inst> shroot

   # sh

   # showfiles -s -c -m > /usr/tmp/configlist

3. Edit the configuration files list (optional).

   If you want to edit the list of configuration files to add additional files or remove unnecessary files, you can do so now by setting your TERM variable and using vi(1):

   # TERM=vt100; export TERM

   # vi /usr/tmp/configlist

4. Create backup configuration files.

   When you are satisified with /usr/tmp/configlist, create the backup configuration files and then quickly replace the password and hosts files (in case of disaster while performing the rest of the procedure):

   # sh -c 'while read fname; do mv $fname $fname.bak; done' < /usr/tmp/configlist

   # cp /etc/hosts.bak /etc/hosts

   # cp /etc/passwd.bak /etc/passwd

   # exit

   # exit

   Inst>

   Note: The < /usr/tmp/configlist portion that appears on the second line of this example should be included at the end of the first line in your entry.

5. Remove target software.

   Remove all currently installed software. At the Inst prompt, enter the commands shown below. It is critical that you not give any other commands at the Inst prompt at this time.

   Inst> set rulesoverride true

   Inst> view targ

   Inst> remove I

   Inst> go

   If you receive a device busy error at this point and receive the Interrupt menu, select Continue. When Inst is finished and you quit, you may be asked if you really want to quit. Enter y for yes.

   Inst> quit

   Please wait ...

   Ready to restart the system. Restart? { y(es), (n)o, (sh)ell, (h)elp } sh

6. Enter the sh command to get a shell prompt.

7. Remove installation history files.

   After escaping to the shell, remove all files that make up what is known as your installation history, and then restart the system:

   # rm -rf /root/var/inst

   # exit

   Ready to restart the system. Restart? { y(es), (n)o, (sh)ell, (h)elp } y

8. Load the miniroot from the older distribution.

   Use the older software distribution that you located at the beginning of this procedure to load the miniroot and invoke Inst; be sure the installation tools and the software version match.

9. Install the older software version.

   Remember that Inst no longer has valid software installation information about this system, so its initial selections are the default selections (see "Required and Default Subsystems"). Use Inst to specifically select for installation any additional software you wish to install.

10. Reboot your system.

11. Merge configuration files.

    In IRIX, merge your config.bak files (listed in /usr/tmp/configlist) with the restored configuration files.

    • If you created a backup copy of customized configuration files (described in "Backing Up the Target Systems") when you were running this release earlier, you should be able to restore the configuration files from that backup and use them. Add any new configuration information that has been added since they were last used.

    • If you have no backup of the current system files, compare the .bak and installed versions of the files in /usr/tmp/configlist, then make the required changes using a process similar to the one for merging configuration files described in "Merging Configuration Files". Be careful not to introduce new features from the later release.