{"id":76903,"date":"2020-04-06T01:42:17","date_gmt":"2020-04-05T23:42:17","guid":{"rendered":"https:\/\/prohoster.info\/blog\/administrirovanie\/samye-zamechatelnye-programmy-unix"},"modified":"2020-04-06T01:42:17","modified_gmt":"2020-04-05T23:42:17","slug":"samye-zamechatelnye-programmy-unix","status":"publish","type":"post","link":"https:\/\/prohoster.info\/ro\/blog\/administrirovanie\/samye-zamechatelnye-programmy-unix","title":{"rendered":"Cele mai remarcabile programe Unix","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Autorul articolului, Douglas MacIlroy, este un matematician, inginer \u0219i programator american. Este cel mai cunoscut pentru dezvoltarea pipeline-ului \u00een sistemul de operare Unix, principiile program\u0103rii orientate pe componente \u0219i pentru c\u00e2teva utilitare originale: spell, diff, sort, join, speak, tr.<\/i> <\/p>\n

Uneori, \u00eent\u00e2lne\u0219ti cu adev\u0103rat programe remarcabile. Dup\u0103 ce m-am scufundat \u00een memorie, am compilat o list\u0103 cu adev\u0103rate bijuterii Unix de-a lungul anilor. \u00cen principal, acestea sunt programe destul de rare \u0219i nu at\u00e2t de necesare. Dar ceea ce le face s\u0103 ias\u0103 \u00een eviden\u021b\u0103 este originalitatea. Nu-mi pot imagina cum mi-ar fi venit singur ideea uneia dintre ele.<\/p>\n

\u00cemp\u0103rt\u0103\u0219i\u021bi, ce programe v-au impresionat \u0219i pe voi at\u00e2t de mult?<\/p>\n

PDP-7 Unix<\/h1>\n

\nPentru \u00eenceput, sistemul PDP-7 Unix. Simplitatea \u0219i puterea sa m-au determinat s\u0103 trec de la un mainframe puternic la o ma\u0219in\u0103 mic\u0103. Aici se afl\u0103 esen\u021ba sistemului ierarhic de fi\u0219iere, un shell separat \u0219i gestionarea proceselor la nivel de utilizator, ceea ce Multics pe mainframe-uri nu a reu\u0219it s\u0103 realizeze dup\u0103 sute de ani de dezvoltare. Deficien\u021bele Unix (de exemplu, structura \u00eenregistr\u0103rilor \u00een sistemul de fi\u0219iere) au fost la fel de instructive \u0219i eliberatoare ca \u0219i nout\u0103\u021bile sale (de exemplu, redirec\u021bionarea intr\u0103rii \u0219i ie\u0219irii \u00een shell).
\n<\/a><\/noindex><\/p>\n

dc<\/h1>\n

\nBiblioteca matematic\u0103 pentru calculatorul de birou cu precizie variabil\u0103 a lui Robert Morris a folosit analiza invers\u0103 a erorilor pentru a determina precizia necesar\u0103 la fiecare pas pentru a atinge precizia dorit\u0103 de utilizator. La conferin\u021ba NATO de inginerie software din 1968, \u00een prezentarea mea despre componentele software, am propus proceduri standard care pot oferi un rezultat cu orice precizie dorit\u0103, dar nu \u0219tiam cum s\u0103 le implementez \u00een practic\u0103. dc r\u0103m\u00e2ne singurul program pe care \u00eel cunosc capabil de a\u0219a ceva.<\/p>\n

typo<\/h1>\n

\nTypo organizeaz\u0103 cuvintele din text \u00een func\u021bie de asem\u0103narea cu restul textului. Gre\u0219elile precum ‘hte’ tind s\u0103 apar\u0103 la sf\u00e2r\u0219itul listei. Robert Morris a afirmat cu m\u00e2ndrie c\u0103 programul va func\u021biona la fel de bine pentru orice limb\u0103. De\u0219i typo nu ajut\u0103 la g\u0103sirea erorilor fonetice, a devenit o adev\u0103rat\u0103 descoperire pentru to\u021bi cei care tasteaz\u0103 text \u0219i a adus multe beneficii \u00eenainte ca verificarea ortografic\u0103 bazat\u0103 pe dic\u021bionar s\u0103 devin\u0103 mai pu\u021bin interesant\u0103, dar mai precis\u0103.<\/p>\n

Typo este la fel de nea\u0219teptat\u0103 \u00een interior pe c\u00e2t este \u00een exterior. Algoritmul de m\u0103surare a similarit\u0103\u021bii se bazeaz\u0103 pe frecven\u021ba de apari\u021bie a trigramelor, care sunt considerate \u00eentr-un aranjament de 26\u00d726\u00d726. \u00centr-o memorie minuscul\u0103 abia exista loc pentru contoare pe un byte, astfel c\u0103 a fost implementat un mecanism de comprimare a numerelor mari \u00een contoare mici. Pentru a evita dep\u0103\u0219irea capacit\u0103\u021bii, contoarele erau actualizate pe o baz\u0103 probabilistic\u0103, men\u021bin\u00e2nd o estimare a logaritmului valorii contorului.<\/p>\n

eqn<\/h1>\n

\nOdat\u0103 cu introducerea fotonab\u0103rului, a devenit posibil, dar extrem de obositor s\u0103 se genereze nota\u021bia matematic\u0103 clasic\u0103. Lorinda Cherry a decis s\u0103 dezvolte un limbaj de descriere de nivel mai \u00eenalt, iar cur\u00e2nd i s-a al\u0103turat Brian Kernighan. Marea lor mutare a fost s\u0103 exprime tradi\u021bia oral\u0103 \u00een format scris, astfel \u00eenc\u00e2t eqn s-a dovedit a fi surprinz\u0103tor de u\u0219or de \u00eenv\u0103\u021bat. Primul s\u0103u tip de preprocesor pentru limbajul de descriere a expresiilor matematice, eqn nu a fost \u00eembun\u0103t\u0103\u021bit semnificativ de atunci.<\/p>\n

struct<\/h1>\n

\nBrenda Baker a \u00eenceput dezvoltarea convertorului s\u0103u Fortan-to-Ratfor \u00een ciuda sfatului meu \u2014 al \u0219efului s\u0103u. M-am g\u00e2ndit c\u0103 acest lucru ar putea duce la o reorganizare special\u0103 a codului surs\u0103. Acesta ar fi lipsit de numerele operatorilor, dar \u00een rest nu ar fi fost mai lizibil dec\u00e2t un cod Fortran bine structurat. Brenda a demonstrat c\u0103 m-am \u00een\u0219elat. Ea a descoperit c\u0103 fiecare program Fortran are o form\u0103 canonica structurat\u0103. Programatorii preferau forma canonic\u0103, mai degrab\u0103 dec\u00e2t ceea ce au scris ini\u021bial.<\/p>\n

pascal<\/h1>\n

\nDiagnosticul sintaxei \u00eentr-un compilator creat de grupul lui Sue Graham la Berkeley a fost cel mai util dintre toate pe care le-am v\u0103zut vreodat\u0103 - \u0219i a fost realizat automat. La o eroare de sintax\u0103, compilatorul propune inserarea unei lexeme pentru a continua analiza sintactic\u0103. Niciun efort de a explica ce nu este \u00een regul\u0103. Cu acest compilator, am \u00eenv\u0103\u021bat Pascal \u00een unei singure serii, f\u0103r\u0103 a avea vreo resurs\u0103 la \u00eendem\u00e2n\u0103.<\/p>\n

p\u0103r\u021bi<\/h1>\n

\nModulul ascuns \u00een pachetul WWB (Writer’s Workbench) p\u0103r\u021bi<\/code> Lorinda Cherry define\u0219te p\u0103r\u021bile de vorbire pentru cuvintele din textul \u00een limba englez\u0103 pe baza doar a unui vocabular limitat, regulilor de ortografie \u0219i gramatic\u0103. Aceast\u0103 anotare permite programului WWB s\u0103 genereze indicatori stilometrici ai textului, cum ar fi prevalen\u021ba adjectivelor, propozi\u021biilor subordonate \u0219i a propozi\u021biilor complexe. C\u00e2nd Lorinda a fost intervievat\u0103 \u00een emisiunea Today de la NBC \u0219i a vorbit despre verificarea inovatoare a gramaticii \u00een textele WWB, aceasta a fost prima men\u021biune a Unix la televizor.<\/p>\n

egrep<\/h1>\n

\nAl Aho a estimat c\u0103 recunoa\u0219terea sa determinist\u0103 a expresiilor regulate va dep\u0103\u0219i recunoa\u0219terea clasic\u0103 nedeterminist\u0103 a lui Ken. Din p\u0103cate, acesta din urm\u0103 finalizase deja procesarea unor expresii regulate complicate \u00een timp ce egrep<\/code> \u00ee\u0219i construiam automatul determinist. Pentru a c\u00e2\u0219tiga aceast\u0103 \u00eentrecere, Al Aho a evitat blestemul cre\u0219terii exponen\u021biale a tabelului de st\u0103ri al automatelor, invent\u00e2nd o metod\u0103 de a construi \u00een timp real doar acele \u00eenregistr\u0103ri din tabel\u0103 care sunt efectiv vizitate \u00een timpul recunoa\u0219terii.<\/p>\n

crabi<\/h1>\n

\nMeta-programul fascinant al lui Luca Cardelli pentru sistemul feronerie Blit genera crabi virtuali care umblau prin spa\u021biul gol al ecranului, t\u0103ind din ce \u00een ce mai mult marginile feroneriilor active.<\/p>\n

C\u00e2teva g\u00e2nduri generale<\/h1>\n

\nDe\u0219i nu este vizibil din exterior, teoria \u0219i algoritmii au jucat un rol crucial \u00een elaborarea majorit\u0103\u021bii acestor programe: typo, dc, struct, pascal, egrep. \u00centr-adev\u0103r, cel mai surprinz\u0103tor este tocmai aplicarea neobi\u0219nuit\u0103 a teoriei.<\/p>\n

Autorii originali ai aproape jum\u0103tate din lista \u2014 pascal, struct, p\u0103r\u021bi, eqn \u2014 au fost femei, ceea ce dep\u0103\u0219e\u0219te semnificativ partea demografic\u0103 a femeilor \u00een domeniul \u0219tiin\u021belor computerizate.<\/p>\n

Douglas McIlroy
\nMartie, 2020<\/i>
\n
Sursa: habr.com<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0410\u0432\u0442\u043e\u0440 \u0441\u0442\u0430\u0442\u044c\u0438 \u0414\u0443\u0433\u043b\u0430\u0441 \u041c\u0430\u043a\u0438\u043b\u0440\u043e\u0439\u00a0\u2014 \u0430\u043c\u0435\u0440\u0438\u043a\u0430\u043d\u0441\u043a\u0438\u0439 \u043c\u0430\u0442\u0435\u043c\u0430\u0442\u0438\u043a, \u0438\u043d\u0436\u0435\u043d\u0435\u0440 \u0438 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0441\u0442. \u041d\u0430\u0438\u0431\u043e\u043b\u0435\u0435 \u0438\u0437\u0432\u0435\u0441\u0442\u0435\u043d \u0440\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u043a\u043e\u0439 \u043a\u043e\u043d\u0432\u0435\u0439\u0435\u0440\u0430 \u0432 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u0435 Unix, \u043f\u0440\u0438\u043d\u0446\u0438\u043f\u043e\u0432 \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u043d\u043e-\u043e\u0440\u0438\u0435\u043d\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u0438 \u043d\u0435\u0441\u043a\u043e\u043b\u044c\u043a\u0438\u0445 \u043e\u0440\u0438\u0433\u0438\u043d\u0430\u043b\u044c\u043d\u044b\u0445 \u0443\u0442\u0438\u043b\u0438\u0442: spell, diff, sort, join, speak, tr. \u0418\u043d\u043e\u0433\u0434\u0430 \u0432\u0430\u043c \u043f\u043e\u043f\u0430\u0434\u0430\u044e\u0442\u0441\u044f \u0434\u0435\u0439\u0441\u0442\u0432\u0438\u0442\u0435\u043b\u044c\u043d\u043e \u0437\u0430\u043c\u0435\u0447\u0430\u0442\u0435\u043b\u044c\u043d\u044b\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u044b. \u041f\u043e\u043a\u043e\u043f\u0430\u0432\u0448\u0438\u0441\u044c \u0432 \u043f\u0430\u043c\u044f\u0442\u0438, \u044f \u0441\u043e\u0441\u0442\u0430\u0432\u0438\u043b \u0441\u043f\u0438\u0441\u043e\u043a \u043d\u0430\u0441\u0442\u043e\u044f\u0449\u0438\u0445 \u0436\u0435\u043c\u0447\u0443\u0436\u0438\u043d Unix \u0437\u0430 \u0432\u0441\u0435 \u0433\u043e\u0434\u044b. \u0412 \u043e\u0441\u043d\u043e\u0432\u043d\u043e\u043c, \u044d\u0442\u043e \u0434\u043e\u0432\u043e\u043b\u044c\u043d\u043e \u0440\u0435\u0434\u043a\u0438\u0435 \u0438 \u043d\u0435 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[688],"tags":[],"class_list":["post-76903","post","type-post","status-publish","format-standard","hentry","category-administrirovanie"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Cele mai remarcabile programe Unix | ProHoster","description":"Autorul articolului, Douglas MacIlroy, este un matematician, inginer \u0219i programator 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