CODEWITHSUNDEEP
rubylinux
kd12
kd12

Reputation: 1351

How can I select the IP address from the output of the `ip route` command using 'src'

If I run below command on terminal it gives IP address value

ip route get 8.8.8.8 | grep -oP '(?<=src )(\d{1,3}.){4}'

But when I run same command with '2>&1' then it returns empty string:

output = ''
IO.popen("ip route get 8.8.8.8 | grep -oP '(?<=src )(\d{1,3}.){4}' 2>&1", 'r+') do |f|
  output = f.read.strip
end
puts output.inspect

Please guide me to understand above scenario. What modifications I need to add to get IP address.

Upvotes: 0

Views: 118

Answers (1)

rodrigo
rodrigo

Reputation: 98486

Nothing to do with the redirection. In Ruby, backslashes in strings must be escaped. Just replace \ with \\:

output = ''
IO.popen("ip route get 8.8.8.8 | grep -oP '(?<=src )(\\d{1,3}.){4}' 2>&1", 'r+') do |f|
  output = f.read.strip
end
puts output.inspect

Upvotes: 2

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