Regular Expressions 101

^start of string

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

Group 1(.)

.any character (except for line terminators)

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

\1the text saved by group 1

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

$end of string, or before its final line terminator

Global pattern flags

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^.*(.).*\1.*$

abcdae