August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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4.9. Wykonywanie poleceń zapisanych w zmiennych
Problem
Chcemy, aby skrypt wykonywał różne polecenia w zależności od konkretnych okoliczności. W jaki sposób można podmieniać realizowane instrukcje?
Rozwiązanie
Istnieje wiele rozwiązań tego problemu — temu właśnie służą skrypty. W kolejnych recepturach zostaną przedstawione różne techniki programistyczne, które umożliwiają wykonanie tak sprecyzowanego zadania. Należą do nich między innymi konstrukcje if-then-else oraz case. Jest jednak jeszcze jeden sposób, charakterystyczny dla powłoki bash. Wartość zmiennej (więcej informacji na temat zmiennych znajduje się w Rozdział 5.) nie musi być jedynie parametrem. Zmienna może przechowywać również treść polecenia.
FN=/tmp/x.x PROG=echo $PROG $FN PROG=cat $PROG ...
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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.