From: Robert Klemme <bob.news@...>
Date: 2004-03-06T22:39:40+09:00
Subject: Re: Ruby translation for UNIX scripting command


"Thomas Luedeke" <tluedeke@excite.com> schrieb im Newsbeitrag
news:20040305181503.955C3B6CC@xprdmailfe14.nwk.excite.com...
>
>
>
>
>
>
>
>
> Quick (and slightly embarassing) newbie question for the Ruby experts. I'm
trying to learn Ruby, and move away from antediluvian UNIX scripting.How do
I make a sequence of pattern matching lines in a file, then extract a
particular field from the line? For example, in UNIX talk if I were
interested in finding all lines with a particular match pattern "test", and
printing the fourth field, I'd do a grep plus awk command such as:grep
"test" file_name | awk ' { print $4 } ' &gt;&gt; output_fileHowever, in my
Ruby books, I don't see any discussion about the function equivalent of
printing a field of the type "$4" (i.e. fourth field). I can get the lines
out of the search file, but I'm not quite sure how to determine
fields.Thanks.TPL

$> ruby -a -n -e 'puts $F[3] if /test/' test-file.txt

If you need to split with another pattern, do

$> ruby -a '-F\s+' -n -e 'puts $F[3] if /test/' test-file.txt

Regards

    robert