re = /^.*?(IDC\w*)[\s\S]*?(?:$|(,\n.*$))(\n|$)/mi
str = ' LTEXT "Width",IDC_WIDTH_TEXT,203,74,22,10
EDITTEXT IDC_WIDTH_IN,244,73,57,12,ES_AUTOHSCROLL | WS_GROUP
CONTROL "Manually scale instances and paper",IDC_RAD_PSCALE_KEYIN,
"Button",BS_AUTORADIOBUTTON | WS_GROUP | WS_TABSTOP,15,89,132,10
CONTROL "Keep drawing instance scale 1.0",IDC_RAD_PSCALE_AUTO,
"Button",BS_AUTORADIOBUTTON,15,104,123,10
CONTROL "Keep drawing paper scale 1.0",IDC_RAD_ISCALE_AUTO,
"Button",BS_AUTORADIOBUTTON,15,119,118,10'
subst = '$1\\n'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html