13. The Danger of sysf

sysf is an administration tools which can modify important system files across an entire network. Configuring or using sysf without a detailed understanding of how it works can seriously damage vital files on many hosts on the network. Although sysf has been thoroughly tested by its author there is no guarantee that it is entirely bug free. It is thus recommended that every users test new configurations on dummy files before deploying then on a real system.

When used properly sysf is a very convenient tool, but it can cause serious damage when used carelessly. In particular here are the major points sysf users must bear in mind.

• Entries that have the flag C, I or U set execute an auxiliary command which run as root. One must double check what these commands do, especially when they create or remove files.
• The command install, first_install and OS_install modify the system files directly. When sysf is not configured properly this can result in erasing a file or replacing it with the wrong one.
• Directory lists are potentially the most dangerous type of entries to use as the command install erases the files that are not listed in the config file. One must thus be very careful to use the correct config file and to configure it properly. One way to avoid problems is to check the differences between the config and the system files by running the command sysf -check or sysf -diff before any modification is implemented. One should also create the config files by using one of the sysf commands (new, archive, makegroup or makedef)
• Before modifying a config file directly, check that it is up to date. If the system file was changed without updating its config file, the changes would be lost.
• Config files should not be symbolic links to other files (except when they point to NONE) as sysf always remove such symbolic link when doing an archive and creates the new config file as a regular file.