regex substitute string until character code example

Example 1: python regex get string before character

You don't need regex for this

>>> s = "Username: How are you today?"
You can use the split method to split the string on the ':' character

>>> s.split(':')
['Username', ' How are you today?']

Example 2: java regex replace all characters before

String s = "the text=text";
String s1 = s.substring(s.indexOf("=")+1);
s1.trim();