E    Update Installation Processing on Existing Files

This appendix describes how the Update Installation process merges existing user customizations into the new, updated versions of the files. The following files and topics are described:

• What are protected system files?

• .new.. files

• .proto.. files

• .PreMRG files

• Merge scripts

• Configured files

• Merging protected system files

• Successful file merges

• Unsuccessful file merges

E.1    Overview of File Preservation During an Update Installation

An Update Installation preserves all user-created files and accounts. It also attempts to preserve customizations made to system files, which are files shipped in the base operating system. To ensure that the customizations are never lost, an Update Installation process creates backup copies of the customized files before updating them. This appendix describes the files used by the update process to preserve file customizations.

E.2    Protected System Files

A protected system file is an operating system file that can be customized by the user. Each protected system file is really three files on your system: the file itself, a .new.. file, and a .proto.. file. As shown in Table E-1, a protected system file that frequently is customized is the /etc/hosts file.

Table E-1:  Protected System File: /etc/hosts

E.2.1    The .new.. Files

An Update Installation prefixes system files with the .new.. prefix to avoid overwriting the configured system file. So, when the new version of the file is loaded, it is loaded as a .new.. file and does not overwrite the user-customized version. An Update Installation also compares the configured file against the .new.. file to determine whether or not you have customized the configured file.

Note

The .new.. files play an important role in the Update Installation process. Do not modify or remove these files.

E.2.2    The .proto.. Files

A file with a .proto.. prefix is a copy of the .new.. file that can be modified. Modify this file only if you are providing site-wide customizations and are using Dataless Management Services (DMS). Otherwise, you should modify the configured version of this file rather than the .proto.. version.

Note

The .proto.. files play an important role in the Update Installation process. Do not remove these files.

The only time these files are modified is if you are using DMS. In that case, the .proto.. files in the dataless areas are modified, not the .proto.. files for the server's operating system. For more information on DMS, see Sharing Software on a Local Area Network.

E.2.3    The .PreMRG Files

The Update Installation process makes copies of all protected system files before updating the system. These copies have a .PreMRG suffix. This ensures that all of your customizations can be restored if the automatic merge operation fails. Using the /etc/hosts file from Table E-1:

• The /etc/hosts file is copied to /etc/hosts.PreMRG

• The /etc/.new..hosts file is copied to /etc/.new..hosts.PreMRG

• The /etc/.proto..hosts file is copied to /etc/.proto..hosts.PreMRG

E.2.4    The .mrg.. Files

A file with a .mrg.. prefix is a script file. This script merges any new functionality added in the new version of the operating system file with your existing configured file.

E.2.5    The Configured File

The /etc/hosts file is the configured file, that is, the file that actually is used and read by the system. This is the file where changes are made during the course of normal system administration and management operations.

E.3    Merging Protected System Files

An updated operating system preserves all prior existing files and customizations. Preserving customizations involves merging new file modifications with existing custom modifications.

The merge script executes if both of the following conditions are true:

• You have customized a configured file, for example /etc/hosts.

• The new version of the operating system has modified the same file.

E.3.1    Successful Merge

After a successful merge, using the /etc/hosts file example, the files shown in Table E-2 are left on your system. The Update Installation process removes the .PreMRG files when the files merge successfully. The file /var/adm/smlogs/it.log contains a log of the merge process.

Table E-2:  Files Left on the System After Successful Merge: /etc/hosts File

E.3.2    Unsuccessful Merge

If the Update Installation is unable to merge your customized Version 4.0G or Version 5.0A file with the new Version 5.1 file, it will create a .FailMRG file and leave the .PreMRG file. In order to ensure that your system operates correctly, the Update Installation will also copy the Version 5.1 file to the configured file so that there is a working version of the file present on the system.

Because the working, configured version of the file is a copy of the Version 5.1 file, it will not contain any of your customizations. You will need to manually add any customizations to the file after the update is complete.

Any lines that exist in the backup copy of the configured file (.PreMRG) and do not exist in the backup of the originally shipped Version 4.0G or Version 5.0A file (.new..file.PreMRG) are your customizations. If the merge failed, using the /etc/hosts example, the files shown in Table E-3 will exist on your system. The file /var/adm/smlogs/upd_mergefail_files contains a list of failed merge files. If you want to determine why the merge failed, you can examine the log of the merge process in the /var/adm/smlogs/it.log and /var/adm/smlogs/update.log files.

Table E-3:  Files Left on the System After a Failed Merge: /etc/hosts File