From: Brian Candler <B.Candler@...>
Date: 2007-05-04T04:03:20+09:00
Subject: Re: search and replace text in files

On Fri, May 04, 2007 at 03:16:37AM +0900, Suraj Kurapati wrote:
> Phil Swenson wrote:
> > I need to search a file for text "InstallDir=" + newline character and
> > replace it with something like:  InstallDir=C\:\\mws71 + newline
> 
> >> "InstallDir=\n".gsub /(InstallDir=)(\n)/, '\1C\:\mws71\2'
> => "InstallDir=C\\:\\mws71\n"
> 
> > My own experimentation with this had problems with writing the back-
> > slashes to the file (it's a requirement of the format to have the back-
> > slashes as in my example).  The string had the back-slashes in it but
> > they didn't get persisted to the file correctly.
> 
> In a single-quoted string, one backslash outputs one backslash.

Except where followed by a single quote or another backslash.

irb(main):001:0> '\\'.length
=> 1
irb(main):002:0> '\''.length
=> 1
irb(main):003:0> '\n'.length
=> 2