# Matches if the string contains a sequence
# of 1 or more lowercase letters
$str =~ /[a-z]+/

##</code><code>##

# Matches if the string consists entirely of
# a sequence of 1 or more lowercase letters,
# optionally followed by a newline
$str =~ /^[a-z]+$/

##</code><code>##

# Matches if the string consists entirely of
# a sequence of 1 or more lowercase letters
$str =~ /^[a-z]+\z/