Chapter 1 Introduction to System Programming

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UNIXLectureNotesChapter1IntroductiontoSy stemProgrammingStewartWeissChapter1Intro ductiontoSystemProgramming UNIXisbasicallyasimpleop eratingsystem,butyouhavetob eageniustounderstandthesimplicity. -DennisRitchie, ,Systemcal lsandlibraries,Processes,loginsandshel ls,Environments,manpages,Users,theroot,a ndgroups,Authentication,Filesystem, lehierarchy,Filesanddirectories,Devicesp ecial les,UNIXstandards,POSIX,Systemprogrammin g,TerminalsandANSIescapesequences,Histor yofUNIX,syscal l,getpid, ductionAmo dernsoftwareapplicationtypicallyneedstom anageb , les,screendisplays, ewrittenasacollectionofco op eratingthreadsorsub-pro cessesthatco ordinatetheiractionswithresp dernop eratingsystemspreventapplicationsoftware frommanagingsystemresourcesdirectly, ,whenrunningonmo dernop eratingsystems,applicationscannotdrawtot hescreendirectlyorreadorwrite erformscreenop erationsor leI/Otheymustusetheinterfacethattheop eratingsystemde ()orfprintf()access lesdirectly,theydonot;theymakecallstosys temroutinesthatdotheworkontheirb eratingsystemforapplicationstousewhenacc essingsystemre-sourcesiscalledtheop eratingsystem'sapplicationprogrammingint erface(API).

The API of an operating system in e ect de nes the means by which an application can ... Figure 1.1: the program gets its input from the keyboard or a disk le, and writes its output to the display screen or to a le on disk. Such programs are called onsolec applications . because the

  Operating, System, Operating systems, Disk