Load­ing the OS

Linux Format - - ESCAPE WINDOWS -

Linux is the ker­nel, that one file in /boot . Ev­ery­thing else, the rest of the GNU/Linux op­er­at­ing sys­tem, runs on top of that ker­nel. The ker­nel is the core of the OS: it sits be­tween the hard­ware and the rest of the soft­ware and ev­ery­thing passes through it, but it’sn’t the com­plete OS. So where ex­actly is the op­er­at­ing sys­tem? Re­mem­ber the root= pa­ram­e­ter that the boot­loader passed to the ker­nel? That’s where ev­ery­thing else starts. It starts with a pro­gram called init, found in /sbin by de­fault. Init’s the first pro­gram the ker­nel runs, it al­ways has the process ID of 1, ev­ery­thing else is a child of it. This is one of the fac­tors cited in the ar­gu­ments against sys­temd, in that it runs as init, as PID1, and such a crit­i­cal part of the sys­tem shouldn’t be messed with. While /sbin/init is the de­fault, you can give the ker­nel a dif­fer­ent lo­ca­tion, as is some­times done with sys­temd, you can even mod­ify this on the boot­loader com­mand line. If you have a prob­lem with your com­puter that pre­vents it com­plet­ing the boot process, you can some­times fix it by adding init=/bin/bash to the ker­nel op­tions in the boot­loader. This means the ker­nel doesn’t even try to load init, but in­stead drops you straight into a shell as root. That is also why you should pre­vent edit­ing of boot op­tions with­out a pass­word on any com­puter that isn’t be­hind locked doors.

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