August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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7.13. Sumowanie zbioru wartości
Problem
Chcemy zsumować kilka wartości liczbowych, które nie zawsze są zapisywane w oddzielnych wierszach.
Rozwiązanie
Zarówno do wydzielania liczb, jak i ich sumowania można wykorzystać narzędzie awk. Oto przykład zsumowania liczb odpowiadających rozmiarom plików, udostępnianych przez polecenie ls –l.
$ ls –l | awk '{sum += $5} END {print sum}'Analiza
Sumowaniu podlega piąte pole listingu wygenerowanego przez instrukcję ls –l. Wiersz wspomnianego listingu ma treść zbliżoną do poniższej:
-rw-r--r-- 1 marek users 116 2005-09-18 13:17 plikdanych
Pojedynczy wiersz składa się więc z następujących pól: praw dostępu, liczby dowiązań, nazwy właściciela, nazwy grupy, rozmiaru (wyrażonego w bajtach), daty, czasu oraz nazwy pliku. ...
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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.