August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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4.6. Zmniejszenie liczby instrukcji if
Problem
Każdy profesjonalny programista musi wziąć sobie do serca zagadnienia opisane w poprzedniej recepturze — „4.5. Ustalenie poprawności wykonania polecenia”. Po uwzględnieniu opisanych tam rozwiązań i zastosowaniu wszystkich instrukcji if sprawdzających kody zakończenia poleceń dochodzimy jednak do wniosku, że treść skryptu jest bardzo nieczytelna. Czy istnieje jakieś rozwiązanie tego problemu?
Rozwiązanie
Powłoka bash udostępnia operator warunkowego wykonania polecenia definiowany za pomocą dwóch znaków ampersand.
$ cd tymczasowy && rm *Analiza
Wiersz złożony z dwóch poleceń rozdzielonych podwójnym znakiem (&) stanowi dla powłoki bash informację o tym, że należy wykonać pierwsze polecenie i, jeśli zakończy ...
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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.