Unix

 

UNIX 1. Give a small introduct introduction ion to UNIX. UNIX is a family of multitasking, multi user operating systems that derive from the original AT & T Unix. Initially intended for use inside the Bell ystem. UNIX operat ope rating ing sys system tem pr provi ovides des sim simple ple too tools ls !hi !hi"h "h per perfor form m lim limite ited, d, !el !ell#d l#de$ e$ned ned fun"tions su"h as %ase me"hanisms for %ooting the "omputer, logging in, running appli" app li"ati ations ons,, sto stori ring ng and re retri trievi eving ng $l $les. es. UNI UNIX X is the $rst $rst por porta%l ta%le e ope operat rating ing system and !as !ritten in  language !hi"h paved !ay in using UNIX in a variety of platforms.

2. What are the types of UNIX you know? un olaris, 'NU()inux, *a" + X

. Name three parts of the UNIX operatin! system with a small description. •

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 The kernel kernel  The kernel kernel of the UNIX is the heart of the operating system. It allo"ates memory and time to the programs and handles the $le stru"ture and "ommuni"ation %et!een %et! een the dier dierent ent parts of the "omputer system su"h as the key%o key%oard ard and the s"reen  The shell  The shell is an interfa"e %et!een the user and the UNIX ker kernel. nel. It resem%le resem%les s -dos %ox that /indo!s displays if you run the "ommand "md. /hen a user logs in, UNIX "he"ks their username and pass!ord and then starts a program "alled the shell. hell interprets the "ommands the user types and transmits them to the kernel to %e exe"uted.  The programs 0rograms are not part of the operating system as su"h, %ut they are logi"al se1uen se1 uen"e "es s of "om "omman mands, ds, dev develo eloped ped for imp implem lement enting ing spe spe"i$ "i$" " tas tasks. ks. The They y usually in"lude appli"ation soft!are running at the user end.

". #escri$e the importance of command shell. It is not possi%le to have a 'UI e1uivalent of all the possi%le things you "an do in a ommand )ine Interfa"e. ome things are dramati"ally faster to do !ith a "ommand line than !ith a 'UI. This espe"ially applies !hen you are a re !orking !ith servers or mainframes in an administrative "apa"ity "apa"ity.. A lot of administrative tasks

 

are many times faster !ith a "ommand line interfa"e 2)I3 "an save a huge amount of moving the mouse around and "li"king. )Is also re1uir re1uire e far less "omputer resour"es resour"es than 'UIs, so they are favored on servers %e"ause you !ant to reserve most of the "omputer4s horsepo!er for the servi"es it provides to users. In UNIX %ased operating systems 2like )inux or *a" + X3 the "ommand line is in"redi%ly useful. It ena%les users to have "omplete "ontrol of the operating o perating systems, and do very "ompli"ated tasks in a fe! keystrok keystrokes. es. )Is are also useful for operating "omputers remotely, %e"ause they use pra"ti"ally no %and!idth, !hereas 'UIs go%%le %and!idth like there4s no tomorro!. 5ou "an manage a do6en ma"hines !ith as many )I !indo!s from one 0 even on very slo! "onne"tions, %ut trying to maintain a do6en 'UI !indo!s "an easily "hoke a slo! net "onne"tion. 7or example, example, !ith a s single ingle UNIX "ommand, I "an "onne"t to an online data%ase, sear"h %y name for the sour"e "ode of an appli"ation, do!nload that sour"e "ode, $nd and do!nload all of its re1uired support $les, "ompile the appli"ation into a %inary $le made spe"i$"ally to run on my "omputer, and install the appli"ation.

%. What do followin! commands in UNIX do? Give an e&ample. •

pwd 2print !orking dire"tory3 8isplays the full pathname of pathname of the "urr "u rrent ent !orking dire"tory dire"tory in  in the standard output.. output 9x: ; p!d (home(!orkingdire"tory

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 <n n= cl <  hanges to lo!er"ase all "hara"ters in a designated line of text. n # pe"i$es the num%er of lines of text to %e "hanged to lo!er"ase. 7ollo! the n argument !ith a spa"e.

 

echo +utputting a string. 9x:

 

date

; e"ho >Text>  Text  Text

 

8isplays(sets a system4s date and time. Also a useful !ay to output(print "urre "urrent nt information !hen !orking in a s"ript $le. 9x:

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; date *on *ay ?@ ??:@?:? 08T ?@C

ls )ists $les and dire"tori dire"tories es !ithin the "urr "urrent ent !orking dire"tory, and admins "an determine !hen "on$guration $les !ere last edited. 9x:

 

; ls Dideos

8o"uments

*usi"

todo.txt

dire"tory3 y3 cd 2"hange dire"tor  Toggle  Toggle %et!een dir dire"tories e"tories "onveniently "onveniently.. 9x:: 9x

 

: :EE= " "d d ga gam mesE sENe Ne! ! 7ol olde derr :EgamesENe! 7older =

mv 2move3  The mv "ommand moves moves a $le to a dierent lo lo"ation "ation or rename renames s a $le. 9x:

 

mv one.txt two.txt  #renames the original $le Fone.txtG to Ft!o.txtG mv three.txt ~/Desktop  ~/Desktop  #m #mov oves es the the $l $le e Ft Fthr hree ee.t .txt xtG G to yo your ur de desk skto top p dire"tory %ut does not rename it. 5ou must spe"ify a ne! $lename to rename a $le.

rmdir 2remove dire"tory3 8eleting a dire"tory 9x:: 9x

 

; rmd mdiir dir dire" e"to torryn ynam ame e

rm 2remove3 8eleting a $le 9x:

rm $le

 

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cat 2"on"atenate3 8isplaying the "ontent of a $le. It "an %e used to read, modify or "on"atenate text $les too. 9x:

; "at $lename