From: Robert Evans <robert.evans@...>
Date: 2007-04-05T04:49:48+09:00
Subject: Re: search a file and replace text

And note, this won't erase any left over old file contents that  
extend beyond the length of the current file, e.g., if the port  
number is a shorter number of characters than the old port number.

Bob


On Apr 4, 2007, at 12:44 PM, Robert Evans wrote:

> Actually, that was pretty sloppy, by opening the file in read-write  
> mode, and then rewinding after the read, we can overwrite it with  
> the changes in a one-liner:
>
> File.open("/tmp/replaceable.txt", 'r+') { |f| newstr = f.read.gsub 
> ('33333', '00000'); f.rewind; f.puts(newstr) }
>
> Bob
>
>
> On Apr 4, 2007, at 12:39 PM, Robert Evans wrote:
>
>> gsub! is destructive - it edits in-place and does not return a  
>> value. You could get a value back from gsub, but then you'd need  
>> to do something with that value.
>>
>> The following worked, though I don't consider it elegant:
>>
>> require 'fileutils'
>>
>> File.open("/tmp/replaceable2.txt", 'w+') do | new_file |
>>     new_file.puts(File.open('/tmp/replaceable.txt', 'r') do |  
>> original_file |
>>                               original_file.read.gsub('30890',  
>> '44444')
>>                           end)
>> end
>> FileUtils.mv("/tmp/replaceable2.txt", "/tmp/replaceable.txt")
>>
>> If you don't want the intermediate file, you could do something  
>> like this:
>>
>> new_str = File.open('/tmp/replaceable.txt', 'r') { | f |  
>> f.read.gsub('30890', '44444') }
>> File.open('/tmp/replaceable.txt', w+) { |f| f.puts new_str }
>>
>> Bob
>> http://www.junitfactory.com/
>>
>>
>>
>> On Apr 3, 2007, at 10:00 AM, phil.swenson@gmail.com wrote:
>>
>>> well I *THOUGHT* I knew how to do it, here's my first crack at it:
>>>
>>>         file_name = base_config_path + '/Caching/tangosol-
>>> coherence.xml'
>>>         File.open(file_name, File::RDWR).each{ |line|
>>>            if line.gsub!(/30890/, port.to_s)
>>>                 puts "tangosol port overridden with %d" % port
>>>                 break
>>>             end
>>>         }
>>>
>>>
>>> The gsub doesn't modify the line, guess it just modifies the string.
>>> How do I actually modify the file itself?
>>>
>>> btw, I did look at rexml but it looked like overkill for this.  I'll
>>> take another look though.
>>>
>>>
>>
>>
>
>