相邻相同字符的正则表达式

Question

I'm looking for a regular expression pattern that can match adjacent 2 same characters, (used for grepping in Linux). For example: Catt Puppet Worry Fool

Answer 1

Something like this with GNU grep?

echo 'Catt Puppet Worry Fool' | grep -E '(.)\1'

or

echo 'Catt Puppet Worry Fool' | grep -oE '(.)\1'

Update:

Try this to get the complete words:

echo 'Catt Puppet Worry Fool' | grep -Po '[^ ]*(.)\1[^ ]*'