Regular Expressions 101

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/
^\s*(?'param'.*):long_name = "(?'def'.*)" ;(\n^.*:units = "(?'units'.*)" ;$)?
/
gm
^ asserts position at start of a line
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Named Capture Group param
(?'param'.*)
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
:long_name = "
matches the characters :long_name = " literally (case sensitive)
Named Capture Group def
(?'def'.*)
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
" ;
matches the characters " ; literally (case sensitive)
3rd Capturing Group
(\n^.*:units = "(?'units'.*)" ;$)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\n matches a line-feed (newline) character (ASCII 10)
^ asserts position at start of a line
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
:units = "
matches the characters :units = " literally (case sensitive)
Named Capture Group units
(?'units'.*)
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
" ;
matches the characters " ; literally (case sensitive)
$ asserts position at the end of a line
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String

Substitution

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