August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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6.3. Sprawdzanie właściwości plików
Problem
Chcemy usprawnić skrypt, dodając do niego funkcję sprawdzenia, czy plik istnieje (przed podjęciem próby odczytania z niego danych), czy plik wyjściowy ma ustawione odpowiednie prawa dostępu (przed próbą zapisania w nim informacji) oraz czy katalog istnieje (przed próbą przejścia do niego). W jaki sposób można zawrzeć tego typu mechanizmy w skrypcie powłoki bash?
Rozwiązanie
W instrukcji test należy uwzględnić odpowiednie operatory sprawdzenia cech pliku. Zdefiniowany wcześniej problem można rozwiązać za pomocą skryptu o następującej treści:
#!/usr/bin/env bash # plik receptury: checkfile # DIRPLACE=/tmp INFILE=/home/krzys/interesujące.dane OUTFILE=/home/krzys/zbiór.wyników if [ -d "$DIRPLACE" ] then cd $DIRPLACE ...
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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.