Is Linux a Unix?
Kind of confused by the two terms. Is there any difference between the two terms?
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This really depends on what you mean by "Unix". Unix has come to mean various things in modern times (and even at the creation point of Linux, it meant multiple things).
In general, Unix is not a particular system, but a specification for systems calling themselves "Unix-like". When people say "Unix" they do not necessarily mean "the proprietary operating system owned by AT&T/Novell/Cisco/whoever now owns it when you're reading this", rather, they usually are referring to the whole spectrum of Unix-like OSes, like AIX, HP-UX, Linux, BSD, Solaris, etc. To this degree, Linux is a FOSS, Unix-like kernel. It is not a direct fork of the original Unix codebase, but it shares many similarities.
Another reason that many people regard Linux to be Unix-like is the fact that it is mostly POSIX-compliant (which is very important for compatibility with other Unix-like systems). Some also associate Linux with Unix because of the initial history of the project -- Linux was largely inspired by (but was not a fork of) MINIX, which is, and was, widely regarded to be an attempt to create a FOSS Unix clone. Many Linux distributions also often implement many tools (or clones/approximations of tools) from Unix, often in the form of GNU Coreutils. Nowadays these tools have been changed a lot (some would argue for the worse, GNU Coreutils is notorious for feature creep), but usually still maintain portability with their original counterparts.
Linux is also indisputably free, open-source software under the GPL, whereas the licensing of the original Unix codebase often depends on who you're asking, and when.