August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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1.6. Cudzysłowy i apostrofy w instrukcjach powłoki
Problem
Chcemy zapoznać się z zasadami stosowania znaków cudzysłowu i apostrofu w instrukcjach powłoki.
Rozwiązanie
Ciągi tekstowe powinny być otaczane znakami apostrofu, chyba że zawierają elementy, które powinny zostać zinterpretowane przez powłokę.
Analiza
Tekst nieotoczony żadnymi znakami cudzysłowu lub apostrofu oraz tekst umieszczony między znakami cudzysłowu jest przez powłokę uznawany za ciąg podlegający interpretacji i podmianie wartości. Oto przykład:
$ echo Kawa kosztuje $5! Kawa kosztuje ! $ echo "Kawa kosztuje $5!" -bash: !": event not found $ echo 'Kawa kosztuje $5!' Kawa kosztuje $5!
W pierwszym przykładzie ciąg $5 jest traktowany jak zmienna, której wartość należy wyświetlić. Ponieważ ...
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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.