# Fastest readline method

**URL:** <https://www.ruby-forum.com/t/fastest-readline-method/183284>\
**Category:** Ruby\
**Created:** [February 11, 2010, 4:56am UTC](https://www.ruby-forum.com/t/fastest-readline-method/183284 "2010-02-11T04:56:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kvetch](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/85e7bf/32.png) [@kvetch](https://www.ruby-forum.com/u/kvetch)\
**Post date:** [February 11, 2010, 4:56am UTC](https://www.ruby-forum.com/t/fastest-readline-method/183284/1 "2010-02-11T04:56:38Z")

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I have a script that parses a bunch of data off the wire and pipes it  
into a fastercsv array. I want to read in a text file and check certain  
columns for matches from the data in the text file. There seems to be  
tons of different ways read in a file and “grep” match for something. I  
would like to do this in the fastest possible method. Reading in the  
file each time could potentially take too long, so I assume reading it  
into memory would be my best bet but perhaps not. I can arrange the  
data in the file in any manner, 1 entry per line, delimited some how or  
whatever.

Does anyone have any suggestions on my best bet to do this?

thanks

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<div class="post-metadata">

**Author:** ![kvetch](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/85e7bf/32.png) [@kvetch](https://www.ruby-forum.com/u/kvetch)\
**Post date:** [February 11, 2010, 11:07am UTC](https://www.ruby-forum.com/t/fastest-readline-method/183284/2 "2010-02-11T11:07:56Z")

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2010/2/11 Kvetch K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> Does anyone have any suggestions on my best bet to do this?  
> I opt for:

File.foreach file\_name do |line|  
if /pattern/ =~ line  
puts “found!”  
end  
end

Because reading is buffered so you do not end up doing a syscall for  
every line and you do not need much memory - which you do if you use  
File.read to slurp in the whole thing. Still, for small to medium  
sized files File.read may still be faster. You need to measure  
different approaches to get figures you can rely on.

Kind regards

robert