grep "twitter \|wikipedia " filename # grep for A or B
grep -P "twitter |wikipedia " filename # grep for A or B
grep "\\\\" filename # grep for a single \
grep -P "\t" filename # grep for tab
grep -h - suppress filename content is found in
grep -A 2 - returns matching line and to lines After
grep -B 2 - returns matching line and to lines Before
Grep Regular Expressions
grep regex
http://www.bo.infn.it/alice/
more about unicode hex etc
