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Newsgroups: comp.os.linux.misc,comp.unix.bsd.misc Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!goanna.cs.rmit.edu.au!news.apana.org.au!cantor.edge.net.au!news.mira.net.au!news.netspace.net.au!news.mel.connect.com.au!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!howland.erols.net!usenet.kornet.nm.kr!agate!news.Stanford.EDU!kithrup.com!sef From: sef@kithrup.com (Sean Eric Fagan) Subject: Re: Linux vs BSD Organization: Kithrup Enterprises, Ltd. Message-ID: <E5GJGG.Ln9@kithrup.com> References: <32DFFEAB.7704@usa.net> <5dphhs$eoi@cynic.portal.ca> <E5G0z9.9Kz@bigbird.telly.org> <5dqmk2$oj2@cynic.portal.ca> Date: Tue, 11 Feb 1997 21:24:15 GMT Lines: 42 Xref: euryale.cc.adfa.oz.au comp.os.linux.misc:157888 comp.unix.bsd.misc:2466 In article <5dqmk2$oj2@cynic.portal.ca>, Curt Sampson <cjs@cynic.portal.ca> wrote: >You've taken two general terms, `kernel' and `OS,' and erased any >distinction between them. I think if you ask most people, they will >say a kernel and an OS are different. An "OS" is an "operating system." A system that operates (which we will assume means "works," not "cuts with sharp shiny knives and removes bits and puts other bits in and then staples or sews it all back up again," although there *are* some OSes that does describe ;)). A kernel, all by itself, does not (usually) operate very well. It kinda just sits there. In fact, if you try to boot nothing but a linux kernel (or a *BSD kernel, or a sconix kernel, or...), you will not have much luck, because one of the first things they try to do is run init -- which is not part of the kernel. It's been many years since any OS of significant size consisted of nothing but a "kernel." In UNIX, the kernel is what manages protections, and organizes hardware resources. That's about it. To actually *use* the system, you have to use other portions of the entire OS. login, for example. And the shell. And the aforementioned init. Now, given the way UNIX was designed and implemented, you could use pretty much any shell you wanted. And you could easily replace the login program -- or even have multiple login-style programs that connected users to the system. About the only thing you couldn't readily replace was init, but you could replace even that with a reboot. There have been many OSes, over the years, where that was *not* the case. Where a single, specific program was used to connect users to the system (i.e., "log in"). And you could not add your own to do that. Where a single, specific program was used to interpret commands entered by the users (i.e., "the shell"). And you could not add your own to do that, or replace it. And so forth. That is one of the strengths of UNIX. And it's the only reason some people (who know UNIX, and little or nothing else) think that a "kernel" is an "operating system."