CODEWITHSUNDEEP
ruby-on-railsruby
Mark Estrada
Mark Estrada

Reputation: 9201

Ruby replace only part of the Matching String

How do I replace only part of the String in a Ruby code?

Supposed I have a text file that contains multiple occurrences of the keyword "JVM_MEM_ARGS_64BIT"

JVM_MEM_ARGS_64BIT="-Xms512m -Xmx512m"

and I only want to replace the first occurrence, I can use the #sub instead of gsub

a.sub('JVM_MEM_ARGS_64BIT="-Xms512m -Xmx512m"', 'JVM_MEM_ARGS_64BIT="-Xms512m -Xmx1024m"')

however not all files contains

JVM_MEM_ARGS_64BIT="-Xms512m -Xmx512m"

some could be

JVM_MEM_ARGS_64BIT="-Xms256m -Xmx512m"

I am not sure how to do this in a ruby code? I can search for the keyword "JVM_MEM_ARGS_64BIT" only but how do I delete the existing value assignment and replace it with JVM_MEM_ARGS_64BIT="-Xms512m -Xmx1024m

Newbie Ruby developer.

Upvotes: 0

Views: 78

Answers (1)

Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121010

String#sub accepts a regular expression as a first param:

replacement = 'JVM_MEM_ARGS_64BIT="-Xms512m -Xmx1024m"'
a.sub(/JVM_MEM_ARGS_64BIT="-Xms\d+m -Xmx\d+m"/, replacement)

Upvotes: 1

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