Perl in a Nutshell, 2nd Edition

Pattern-Matching Operators

The following list defines Perl’s pattern-matching operators. Some of the operators have alternative “quoting” schemes and have a set of modifiers that can be placed directly after the operators to affect the match operation in some way.

m/ pattern /gimosxe

Searches a string for a pattern match. Modifiers are :

Modifier	Meaning
g	Match globally, i.e., find all occurrences.
i	Do case-insensitive pattern matching.
m	Treat string as multiple lines.
o	Compile pattern only once.
s	Treat string as single line.
x	Use extended regular expressions.

If / is the delimiter, then the initial m is optional. With m, you can use any pair of non-alphanumeric, non-whitespace characters as delimiters.

? pattern ?

This operator is just like the m/ pattern / search, except it matches only once.

qr/ pattern /imosx

Creates a precompiled regular expression from pattern, which can be passed around in variables and interpolated into other regular expressions. The modifiers are the same as those for m// above.

s/ pattern / replacement /egimosx

Searches a string for pattern and replaces any match with the replacement text. Returns the number of substitutions made, which can be more than one with the /g modifier. Otherwise, it returns false (0). If no string is specified via the =~ or !~ operator, the $_ variable is searched and modified. Modifiers are:

Modifier	Meaning
e	Evaluate the right side as an expression.
g	Replace globally, i.e., all occurrences.
cg	Continue search after g failed. ...