August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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14.8. Wyznaczanie bezpiecznej wartości umask
Problem
Chcemy mieć pewność, że wykorzystywana wartość umask nie stanowi zagrożenia dla systemu.
Rozwiązanie
Dzięki wbudowanemu poleceniu powłoki umask można na początku każdego skryptu ustawić poprawną, znaną wartość maski:
# Wyznaczenie bezpiecznej wartości zmiennej umask i wprowadzenie nowego ustawienia. # Działanie nie obejmuje plików powstałych w wyniku wcześniejszego przekierowania # danych # Wartość 002 odpowiada prawom 0774, wartość 077 odpowiada prawom 0700 itd. UMASK=002 umask $UMASK
Analiza
Powołanie zmiennej $UMASK pozwala na wyznaczenie różnych wartości masek w różnych miejscach programu. Oczywiście, można by bez problemu wykonać to samo zadanie bez tworzenia zmiennej:
umask 002
Podpowiedź
Należy ...
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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.