Linked by Thom Holwerda on Fri 21st Oct 2011 23:17 UTC, submitted by jello

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Member since:
2007-02-17
To be clear, the Linux kernel was also written from scratch. The Linux kernel contains no UNIX code.
http://en.wikipedia.org/wiki/File:Unix_history-simple.svg
In the diagram above, Linux is represented by the second column from the left. Unlike Mac OSX, Linux has no UNIX or BSD predecessors.
Unlike Mac OSX, Linux is not a certified implementation of UNIX.
The Linux kernel is UNIX-like, since it is designed to be POSIX compliant after all, but it is not UNIX, it contains no UNIX code, and it is not therefore based on UNIX.
UNIX userland applications will not run on Linux as there is no ABI or API compatibility. Error codes, for example, are different, because Linus mixed them up (unintentionally). X11 applications can run on Linux if they are re-compiled for Linux, binaries will not run. Bash scripts will run.
Edited 2011-10-25 06:16 UTC