in reply to How to remove all repeating characters in a string in place

Yes, alternance operator in regex | and the global regex modifier g 
perl -e "$ARGV[0]=~s/a|b|f//g;print $ARGV[0]" aaabbcdeffgh
cdegh

[download]

The s///g behaviour is introduced in perlrequick's Search and Replace part and in the Global Matching part of perlretut

HtH

L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

In Section Seekers of Perl Wisdom