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IBM developerWorks: Awk by example, Part 2 - Records, loops, and arrays

Jan 14, 2001, 16:39 (0 Talkback[s])
(Other stories by Daniel Robbins)

[ Thanks to Raj Singh for this link. ]

"In this sequel to his previous intro to awk, Daniel Robbins continues to explore awk, a great language with a strange name. Daniel will show you how to handle multi-line records, use looping constructs, and create and use awk arrays. By the end of this article, you'll be well versed in a wide range of awk features, and you'll be ready to write your own powerful awk scripts."

"Awk is an excellent tool for reading in and processing structured data, such as the system's /etc/passwd file. /etc/passwd is the UNIX user database, and is a colon-delimited text file, containing a lot of important information, including all existing user accounts and user IDs, among other things. In my previous article, I showed you how awk could easily parse this file. All we had to do was to set the FS (field separator) variable to ":".

"By setting the FS variable correctly, awk can be configured to parse almost any kind of structured data, as long as there is one record per line. However, just setting FS won't do us any good if we want to parse a record that exists over multiple lines. In these situations, we also need to modify the RS record separator variable. The RS variable tells awk when the current record ends and a new record begins."

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