/**

• Troulakis Giorgos Rafail
• C shell csd_sh */

To shell ksekinaei kalontas tin sunartisi vasikis ektypwsis tou.Diladi auti pou kanei print to username to path kai perimenei na dextei entoli.Me mia atermoni epanalipsi loipon t shell pote den kanei exit ean den tou dwseis esu tin entoli exit kai perimenei gia entoles. Arxika opws eipame dexete tin prwti entoli elegxwntas ama einai exit i cd i enviroment kai kalwntas mia sunartisi pou kanei to parsing kanei tis antistoixes entoles(Stin sunartisi parsing ektos apo to parse elegxo kai ti typou redirection einai to opoio tha xrisimeusei stin sunexeia).Se autes tis periptwseis den xreiazetai na ginei fork se mia diergasia. Stin sunexeia elegxei ama einai pipe kai kanei arxika to pipe parsing stin main(logo elipsis xronou den ftiaxtike sunartisi kai giauto).Kai gia na ksekinisei na kanei kapoia fork diaxwrizetai se pipes entoles i kanonikes,Stin kanonikes entoles kanei kanonika fork kai elegxei ean einai entoli gia execution enos ektelesimou arxeiou ean einai csdtime i ean einai oi upoloipes.Ektelei kanonika me tis exec entoles tis vasikes entoles tou unix tis opoies tis vriskoume sto bin fakelo kai meta elgxei ean einai input i output tupou entoles gia na kanei tis antistixes energeies xrisimopoiontas to dup2.To ti tupou einai to exoume anakalupsei apo tin sunartisi parsing pou kanoume stin arxi kathe entolis me mia metavliti type of redirection opote gnwrizoume ama theloume na kanoume write append i read antistoixa.En to emtaksu i parrent process pou exei dimiourgithei apo to fork perimenei panta to child na teleiwsei tin douleia tou me wait kai meta pali apo tina rxi gyrnaei stin vasiki default arxiki othoni pou perimenei na dwseis tin epomeni entoli.Stis pipes mpainei kai ftiaxnei pipes kai kanei prwta tin prwti kai eisagei tin eksodo tis stin 3i.episis telos otan pairnei sto telos ton xaraktira & to paidi trexei sto background xwris na kanei wait o pateras