August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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4.5. Ustalenie poprawności wykonania polecenia
Problem
Chcemy wykonać pewne polecenia, ale część z nich powinna zostać zrealizowana tylko w przypadku, w którym inne instrukcje zostaną wykonane poprawnie. Przykładem może tu być konieczność zmiany katalogu (za pomocą polecenia cd) na katalog tymczasowy i usunięcia z niego wszystkich plików. Oczywiście, nie wolno dopuścić do usunięcia wszystkich plików, jeżeli operacja zmiany katalogów nie została wykonana poprawnie (na przykład z uwagi na brak odpowiednich praw dostępu lub błąd w zapisie nazwy katalogu).
Rozwiązanie
Należy wykorzystać kod zakończenia polecenia cd (udostępniany w zmiennej $?) oraz instrukcję warunkową if. Polecenie rm będzie wówczas mogło zostać wywołane tylko po poprawnym zakończeniu ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.