Regular Expressions 101

Non-Capturing Group(?:\s*key1\s+(?'key1'.+))?

?repeats the group contents below at most once:

\s*any whitespace character, repeated any number of times

key1the literal text key1 (case sensitive)

\s+any whitespace character, repeated at least once

Group key1(?'key1'.+)

.+any character (except for line terminators), repeated at least once

Non-Capturing Group(?:\s*key2\s+(?'key2'.+))?

?repeats the group contents below at most once:

\s*any whitespace character, repeated any number of times

key2the literal text key2 (case sensitive)

\s+any whitespace character, repeated at least once

Group key2(?'key2'.+)

.+any character (except for line terminators), repeated at least once

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?:\s*key1\s+(?'key1'.+))?(?:\s*key2\s+(?'key2'.+))?

New

 key1 p1, p2 ,p3 key2 p4,p5