Extract lines with regular expressions

Ruby
1

I am a newb trying to take a list of data in a text file and print out a
new list of lines that contain certain characters…
I am not too worried about the actual regex - I can figure that out -
but I cannot seem to get it to implement correctly.

I found the following online (fepus.net)

print only lines that match a regular expression (emulates ‘grep’)

$  ruby -pe 'next unless $_ =~ /regexp/' < file.txt

and it does exactly what I want, but…

how do I use this (or something similar, ie grep) in a .rb script?

I have tried this:
vl_stops.each do |vl_stops|
puts “#{vl_stops}”
search = Regexp.new(“^\b(#{vl_stops}:)\w*”)
files.each do |file|
f = File.open(directory+file)
f.grep(search)
puts #what goes here? line?
end
f.close
end
puts
end
based on something I found here
(http://www.rousette.org.uk/blog/archives/2004/10/21/gtd-using-text-files/)

But I am not sure how to seal the deal, as it were…
Any thoughts would be appreciated.
Thanks!

2

On 21.04.2008 07:49, Michael Dore wrote:

and it does exactly what I want, but…
puts #what goes here? line?
Thanks!
files.each do |file|
File.open(directory+file) do |f|
puts f.grep(search)
end

Or, for large files

files.each do |file|
File.open(directory+file) do |f|
   f.each do |line|
     puts line if search ~= line
   end
end

Kind regards

robert

3

Michael Dore wrote:

I have tried this:

vl_stops.each do |vl_stops|

First, you might try dreaming up more than one variable name.

Second, if you are searching for simple strings, like ‘hello’, you can
do this:

search_string = ‘hello’

IO.foreach(“data.txt”) do |line|
if line.include?(search_string)
puts line
end
end