How to get all digits from string regexp ruby

Without regex:

"Lorem 123 ipsum 456 879".delete('^0-9') #=>"123456879"

Just replace everything else.

result = subject.gsub(/[^\d]/, '')

Ref this

result = subject.gsub(/\D/, '')  

"Lorem 123 ipsum 456 879".scan(/\d+/).join # => "123456879"