Regular Expressions

regular expressions are patterns used to match text
REs use normal AND metacharacters
REs match anywhere on a line
for example: ape, will match grape,ape,runescape, but not A.P.E.
by default, case-sensitive
searching for default: will require the colon to follow the word default
backslashes escape metacharacters
awk, sed, perl, grep, vi all use REs