Introduction to Linux

1.1 History??

1.1.1 UNIX??

In?order?to?understand?the?popularity?of?Linux,?we?need?to?travel?back?in?time,?about?30?years?ago...??

Imagine?computers?as?big?as?houses,?even?stadiums.?While?the?sizes?of?those?computers?posed?substantial?problems,?there?was?one?thing?that?made?this?even?worse:?every?computer?had?a?different?operating?system.?Software?was?always?customized?to?serve?a?specific?purpose,?and?software?for?one?given?system?didn't?run?on?another?system.?Being?able?to?work?with?one?system?didn't?automatically?mean?that?you?could?work?with?another.?It?was?difficult,?both?for?the?users?and?the?system?administrators.??

Computers?were?extremely?expensive?then,?and?sacrifices?had?to?be?made?even?after?the?original?purchase?just?to?get?the?users?to?understand?how?they?worked.?The?total?cost?of?IT?was?enormous.??

Technologically?the?world?was?not?quite?that?advanced,?so?they?had?to?live?with?the?size?for?another?decade.?In?1969,?a?team?of?developers?in?the?Bell?Labs?laboratories?started?working?on?a?solution?for?the?software?problem,?to?address?these?compatibility?issues.?They?developed?a?new?operating?system,?which?was??

simple?and?elegant??

written?in?the?C?programming?language?instead?of?in?assembly?code??

able?to?recycle?code.??

The?Bell?Labs?developers?named?their?project?"UNIX."??

The?code?recycling?features?were?very?important.?Until?then,?all?commercially?available?computer?systems?were?written?in?a?code?specifically?developed?for?one?system.?UNIX?on?the?other?hand?needed?only?a?small?piece?of?that?special?code,?which?is?now?commonly?named?the?kernel.?This?kernel?is?the?only?piece?of?code?that?needs?to?be?adapted?for?every?specific?system?and?forms?the?base?of?the?UNIX?system.?The?operating?system?and?all?other?functions?were?built?around?this?kernel?and?written?in?a?higher?programming?language,?C.?This?language?was?especially?developed?for?creating?the?UNIX?system.?Using?this?new?technique,?it?was?much?easier?to?develop?an?operating?sys