CODEWITHSUNDEEP
ruby-on-railsruby
Antonio MG
Antonio MG

Reputation: 20410

Replacing all the line containing string in Ruby

I need to replace a variable in a Makefile in Ruby

For ex (inside the Makefile):

VAR = 123

What I'm doing is:

puts text.gsub("VAR = 123", "VAR_NEW = 456")

The problem is that I don't know the value, so I would like to use a regular expresion to replace ALL the line containing VAR =

What regular expresion can I use? Can I use a different approach?

Upvotes: 0

Views: 303

Answers (4)

ichigolas
ichigolas

Reputation: 7725

You can use a regexp like this: 

var = 123
new = 456
text.gsub(/\b#{var}\s?= .+/, "var = #{new}")

Upvotes: 1

graudeejs
graudeejs

Reputation: 349

This tool will help you figure it out http://rubular.com/

Perhaps this

test.gsub(/^(VAR=\s*(['"]?))\d+\2/, $1 + "456" + $2)

That is, if you only want to change value of variable

Edit:

test.gsub(/^(VAR=\s*(['"]?))\d+\2\s*$/, $1 + "456" + $2)

Edit 2

test.gsub(/^(VAR=\s*(['"]?)).*\2\s*$/, $1 + "456" + $2)

Upvotes: 1

DigitalRoss
DigitalRoss

Reputation: 146053

 q.sub /VAR = .*/, 'VAR = 456' # replace one line

Upvotes: 3

Alexander Randa
Alexander Randa

Reputation: 868

If i understand correct, you can do this:

irb(main):001:0> text = <<EOF
irb(main):002:0" VAR1 = 111
irb(main):003:0" VAR2 = 222
irb(main):004:0" EOF
=> "VAR1 = 111\nVAR2 = 222\n"
irb(main):005:0> puts text
VAR1 = 111
VAR2 = 222
=> nil
irb(main):007:0> text.gsub!(/^VAR2\s\=\s\d+/, "NEW_VAR = 555")
=> "VAR1 = 111\nNEW_VAR = 555\n"
irb(main):008:0> puts text
VAR1 = 111
NEW_VAR = 555
=> nil

Upvotes: 1

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