Theo de Raadt, who works on the open source operating system OpenBSD, calls Linux "rubbish" and claims people only stick with it because they don't know any better.

OpenBSD differs from Linux in that Linux is a clone of UNIX, whereas OpenBSD is based on an actual UNIX variant called Berkeley Software Distribution. Naturally, opinions of Linux in the OpenBSD camp are pretty poor, despite the fact that Linux is immensely more popular than all of the open source BSD versions. Theo de Raadt claims that Linux owes its success purely to the support it gets from the big hardware makers like HP and IBM.

"These companies used to have to pay to develop UNIX. They had in-house engineers who wrote new features when customers wanted them. Now they just allow the user community to do their own little hacks and features, trying to get to the same functionality level, and they're just putting pennies into it," De Raadt says.
Theo de Raadt claims that the quality of code coming from his project is far superior to "the slapdash Linux movement" and that the focus of Linux is not on quality.

Linus Torvalds, the creator of the Linux kernel, has called De Raadt "difficult", and has not commented further.