I'm not sure if it's what you're looking for (i.e. doesn't break something else somewhere else...) but I find that: 
 perl -e '$string="abcX123"; $string =~ /X+?(\S+)/; print $1;'

[download]
works for me... HTH

In reply to Re: Capturing everything after an optional character in a regex? by serf
in thread Capturing everything after an optional character in a regex? by Anonymous Monk

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