[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

minor documentation suggestion for FS values and "whitespace" in general

From: Ed Morton
Subject: minor documentation suggestion for FS values and "whitespace" in general
Date: Mon, 23 Mar 2020 10:02:03 -0400
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0

I was just looking up which exact characters get included in the set of field separators when FS is " " (the default value) and got confused by this in the gawk documentation:

   Class    Meaning
   [:blank:]    Space and TAB characters
   [:space:]    Space characters (these are: space, TAB, newline,
   carriage return, formfeed and vertical tab)

   FS == " "
        Fields are separated by runs of *whitespace*. Leading and
   trailing whitespace are ignored. This is the default.
   /(bold added by me)/

I took the last statement above to mean that FS would be the set of characters defined by the [:space:] character class but it's not since FS doesn't include carriage return (\r) nor vertical tab (\v) (I didn't bother checking others)when FS is " ", neither is it the [:blank:] character class since it includes newlines (\n). Instead it seems to be [:blank:] plus newline and that's supported by the POSIX spec if we assume by <blank> they mean [:blank:]:

   ...by default, a field is a string of non- <blank> non- <newline>

But what does newline mean in all of the above? Is it always linefeed (\n) on all platforms or is it LF (\n) on UNIX and CRLF (\r\n) on Windows or something else? I really don't know.

So - maybe you could update the documentation to say "Fields are separated by runs of the whitespace (i.e. [:blank:] plus linefeed characters)" or similar? I couldn't find anywhere in the documentation that states exactly which characters  FS includes when assigned " " nor what exactly is meant by "whitespace" throughout the documentation and I think that one tweak to provide a clear definition of the term "whitespace" would clarify all of it.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]