Differences between Windows registry and UNIX/Linux approach [closed]

There is no real cognate in UNIX, but as wollud1969 says, /etc comes close. That, though, is only part of the story. You'd also need to consider things under /var (for information about installed software, running services, etc), /usr/local/etc (at least on FreeBSD and certain Linux distros) for configuration information for installed third party apps, and of course each user's dotfiles, which customise how software works for them (roughly equivalent the the HK_CURRENT_USER hive in the registry). Then there's /dev for device interfaces, /proc for running process data, and the kernel itself (either through sysctl, a kernfs virtual file system, etc). Depending on your particular platform, there may be other places to look, too.

The primary advantage in the UNIX approach, from my perspective as a UNIX user these last 12 years, is that application config files, wherever they live, are usually just plain old text files, so can be read and edited by plain old humans. (Except, possibly, the sendmail config file, but that's a completely different religious war...). Many applications (browsers, desktop apps, etc) create config files for you, but they are text files, and the apps usually won't stop working if those files are then edited by hand, provided the edits don't break their syntax. The downside, though, is that there is no universal config language, so you need to learn the syntax for each app you manage. In reality, though, this is only a small annoyance at worst.

The Windows Registry was developed, at least in part, to address a similar state of affairs that was deemed problematic by Microsoft, where application ini files were not centrally managed, with no strict control on what values went in them, and no standard location for software to put them. The registry fixes some of those concerns (it is centrally managed, with specific data types that can be stored in it), but its disadvantages are its binary format, so that even experienced Windows admins need to use a GUI tool to look at it, it's prone to getting corrupted if you lose power, and not all software authors are sufficiently conscientious to clean up after themselves when you decide to uninstall their kewl shareware app. And, as with almost any other file in Windows, it's entirely possible for the various components of the registry to become fragmented on disk, resulting in painfully slow read and update operations. There is no requirement for software to make use of the registry, and even Microsoft's own .NET platform uses XML files instead.

The Wikipedia page about the registry is quite informative.