What I have:
@user653434 text and so
@user9659333 text and so
grep -P (requires GNU
$ grep -oP '(?<=@)\w+' File user653434 user9659333
-o tells grep to print only the match.
-P tells grep to use Perl-style regular expressions.
(?<=@) tells sed that
@ must precede the match but the
@ is not included in the match.
\w+ matches one or more word characters. This is what grep will print.