November 2012
Intermediate to advanced
888 pages
54h 46m
Polish
Content preview from Ruby. Receptury
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20.9. Przechwytywanie strumienia wyjściowego i informacji o błędach z polecenia powłoki w systemie Unix
Problem
Chcemy uruchomić zewnętrzny program tak jak w „20.8. Sterowanie zewnętrznym procesem za pomocą metody popen”, ale dodatkowo chcemy przechwytywać standardowy strumień informacji o błędach. Metoda popen daje dostęp tylko do standardowego wyjścia.
Rozwiązanie
Można skorzystać ze standardowej biblioteki języka Ruby — open3. Jej metoda popen3 pobiera blok kodowy, do którego przekazuje trzy strumienie wejścia-wyjścia, po jednym dla (odpowiednio): standardowego wejścia, standardowego wyjścia i standardowej informacji o błędach.
Załóżmy, że wykonaliśmy uniksowe polecenie ls w celu wyświetlenia zawartości nieistniejącego katalogu. ...
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