Regular Expressions 101

Pro

1st Alternative(?s:\A.*?^keyword1|^keyword2.*)(*SKIP)(*F)

Group with flags gms(?s:\A.*?^keyword1|^keyword2.*)

s modifier: single line. Allows a dot to match line terminators

1st Alternative\A.*?^keyword1

\Astart of string

.*?any character, repeated any number of times

^start of line

keyword1the literal text keyword1 (case sensitive)

2nd Alternative^keyword2.*

^start of line

keyword2the literal text keyword2 (case sensitive)

.*any character, repeated any number of times

(*SKIP)acts like (*PRUNE), but the next unanchored match attempt starts where (*SKIP) was reached instead of at the next subject character

(*F)forces the current match attempt to fail at this position

2nd Alternative^.*?(?=\h---)

^start of line

.*?any character (except for line terminators), repeated any number of times

Positive Lookahead(?=\h---)

\hany horizontal whitespace character

---the literal text ---

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.

25 tokens

Regular Expression

(?s:\A.*?^keyword1|^keyword2.*)(*SKIP)(*F)|^.*?(?=\h---)

New

badstring ---
useless data
keyword1 ---
usless data
string 1 ---
random number of useless lines of characters across newlines
string 2 ---
more useless stuff
keyword2 ---
useless data
dumb badstring keyword2 ---