Perl in a Nutshell, 2nd Edition

Logical Operators

Perl provides the && (logical AND) and || (logical OR) operators. They evaluate from left to right testing the truth of the statement.

Example	Name	Result
$a && $b	And	$a if $a is false, $b otherwise
$a || $b	Or	$a if $a is true, $b otherwise

For example, an oft-appearing idiom in Perl programs is:

open(FILE, "somefile") || die "Cannot open somefile: $!\n";

In this case, Perl first evaluates the open function. If the value is true (because somefile was successfully opened), the execution of the die function is unnecessary and is skipped.

Perl also provides lower-precedence and and or operators that are more readable.