From: Eric Hodel <drbrain@...7.net>
Date: 2004-07-03T03:54:42+09:00
Subject: Re: Help with one-liner

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Philip Mateescu (pmateescu@novosadhayes.com) wrote:

> Hello,
>=20
> I'm having problems with an one-liner (ruby 1.6.8 (2003-02-25)=20
> [i386-cygwin]).
>=20
> My one liner sample:
>=20
> $ ping localhost | ruby -e '$<.readlines.each { |line|  line.chomp!();=20
> puts(line + "---\n");  }'
>=20
> I would expect it to put --- at the end of each line. Instead it=20
> replaces the first 3 chars of each line with "---"
>=20
> What am I doing wrong? And why? :)

The real reason has been adequately addressed in the rest of this
thread.

If you want #chomp to remove the line-ending, you must chomp with $/,
which is the input record separator ($/ is cross-platform, so your
one-liner will work anywhere):

ruby -e "readlines.each {|l| puts %!#{l.chomp $/}!}"

Note that you don't have to use $< with -e, because readlines is a
Kernel method that reads from $< by default (I don't even know what $<
is).

Note that I used %!...! for the interpolated string to get around the
stupid windows shell.  You can use just about any character after the %,
except for a few special ones ([qQsSwW] I think).  (I typically use ! or
^.)

Note that I also used string interpolation, %!#{...}--!, rather than
storing to a temporary and using string concatenation.  String
interpolation is both faster to type and faster to interpret.

To find out what all the special global variables are ($<, $:, $/, etc)
see English.rb in your ruby library directory.

--=20
Eric Hodel - drbrain@segment7.net - http://segment7.net
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