Meta­character(s) Description Example[64]
. Normally matches any character except a newline.
Within square brackets the dot is literal. 
$string1 = "Hello World\n";
if ($string1 =~ m/...../) {
  print "$string1 has length >= 5.\n";
}

Output: 

Hello World
 has length >= 5.
( ) Groups a series of pattern elements to a single element.
When you match a pattern within parentheses, you can use any of $1, $2, ... later to refer to the previously matched pattern. Some implementations may use a backslash notation instead, like \1, \2. 
$string1 = "Hello World\n";
if ($string1 =~ m/(H..).(o..)/) {
  print "We matched '$1' and '$2'.\n";
}

Output: 

We matched 'Hel' and 'o W'.
+ Matches the preceding pattern element one or more times. 
$string1 = "Hello World\n";
if ($string1 =~ m/l+/) {
  print "There are one or more consecutive letter \"l\"'s in $string1.\n";
}

Output: 

There are one or more consecutive letter "l"'s in Hello World.
? Matches the preceding pattern element zero or one time. 
$string1 = "Hello World\n";
if ($string1 =~ m/H.?e/) {
  print "There is an 'H' and a 'e' separated by ";
  print "0-1 characters (e.g., He Hue Hee).\n";
}

Output: 

There is an 'H' and a 'e' separated by 0-1 characters (e.g., He Hue Hee).
? Modifies the *, +, ? or {M,N}'d regex that comes before to match as few times as possible. 
$string1 = "Hello World\n";
if ($string1 =~ m/(l.+?o)/) {
  print "The non-greedy match with 'l' followed by one or ";
  print "more characters is 'llo' rather than 'llo Wo'.\n";
}

Output: 

The non-greedy match with 'l' followed by one or more characters is 'llo' rather than 'llo Wo'.
* Matches the preceding pattern element zero or more times. 
$string1 = "Hello World\n";
if ($string1 =~ m/el*o/) {
  print "There is an 'e' followed by zero to many ";
  print "'l' followed by 'o' (e.g., eo, elo, ello, elllo).\n";
}

Output: 

There is an 'e' followed by zero to many 'l' followed by 'o' (e.g., eo, elo, ello, elllo).
{M,N} Denotes the minimum M and the maximum N match count.
N can be omitted and M can be 0: {M} matches "exactly" M times; {M,} matches "at least" M times; {0,N} matches "at most" N times.
x* y+ z? is thus equivalent to x{0,} y{1,} z{0,1}. 
$string1 = "Hello World\n";
if ($string1 =~ m/l{1,2}/) {
  print "There exists a substring with at least 1 ";
  print "and at most 2 l's in $string1\n";
}

Output: 

There exists a substring with at least 1 and at most 2 l's in Hello World
[…] Denotes a set of possible character matches. 
$string1 = "Hello World\n";
if ($string1 =~ m/[aeiou]+/) {
  print "$string1 contains one or more vowels.\n";
}

Output: 

Hello World
 contains one or more vowels.
| Separates alternate possibilities. 
$string1 = "Hello World\n";
if ($string1 =~ m/(Hello|Hi|Pogo)/) {
  print "$string1 contains at least one of Hello, Hi, or Pogo.";
}

Output: 

Hello World
 contains at least one of Hello, Hi, or Pogo.
\b Matches a zero-width boundary between a word-class character (see next) and either a non-word class character or an edge; same as

(^\w|\w$|\W\w|\w\W). 

$string1 = "Hello World\n";
if ($string1 =~ m/llo\b/) {
  print "There is a word that ends with 'llo'.\n";
}

Output: 

There is a word that ends with 'llo'.
\w Matches an alphanumeric character, including "_";
same as [A-Za-z0-9_] in ASCII, and
[\p{Alphabetic}\p{GC=Mark}\p{GC=Decimal_Number}\p{GC=Connector_Punctuation}]

in Unicode,[51] where the Alphabetic property contains more than Latin letters, and the Decimal_Number property contains more than Arab digits. 

$string1 = "Hello World\n";
if ($string1 =~ m/\w/) {
  print "There is at least one alphanumeric ";
  print "character in $string1 (A-Z, a-z, 0-9, _).\n";
}

Output: 

There is at least one alphanumeric character in Hello World
 (A-Z, a-z, 0-9, _).
\W Matches a non-alphanumeric character, excluding "_";
same as [^A-Za-z0-9_] in ASCII, and
[^\p{Alphabetic}\p{GC=Mark}\p{GC=Decimal_Number}\p{GC=Connector_Punctuation}]

in Unicode. 

$string1 = "Hello World\n";
if ($string1 =~ m/\W/) {
  print "The space between Hello and ";
  print "World is not alphanumeric.\n";
}

Output: 

The space between Hello and World is not alphanumeric.
\s Matches a whitespace character,
which in ASCII are tab, line feed, form feed, carriage return, and space;
in Unicode, also matches no-break spaces, next line, and the variable-width spaces (amongst others). 
$string1 = "Hello World\n";
if ($string1 =~ m/\s.*\s/) {
  print "In $string1 there are TWO whitespace characters, which may";
  print " be separated by other characters.\n";
}

Output: 

In Hello World
 there are TWO whitespace characters, which may be separated by other characters.
\S Matches anything but a whitespace. 
$string1 = "Hello World\n";
if ($string1 =~ m/\S.*\S/) {
  print "In $string1 there are TWO non-whitespace characters, which";
  print " may be separated by other characters.\n";
}

Output: 

In Hello World
 there are TWO non-whitespace characters, which may be separated by other characters.
\d Matches a digit;
same as [0-9] in ASCII;
in Unicode, same as the \p{Digit} or \p{GC=Decimal_Number} property, which itself the same as the \p{Numeric_Type=Decimal} property. 
$string1 = "99 bottles of beer on the wall.";
if ($string1 =~ m/(\d+)/) {
  print "$1 is the first number in '$string1'\n";
}

Output: 

99 is the first number in '99 bottles of beer on the wall.'
\D Matches a non-digit;
same as [^0-9] in ASCII or \P{Digit} in Unicode. 
$string1 = "Hello World\n";
if ($string1 =~ m/\D/) {
  print "There is at least one character in $string1";
  print " that is not a digit.\n";
}

Output: 

There is at least one character in Hello World
 that is not a digit.
^ Matches the beginning of a line or string. 
$string1 = "Hello World\n";
if ($string1 =~ m/^He/) {
  print "$string1 starts with the characters 'He'.\n";
}

Output: 

Hello World
 starts with the characters 'He'.
$ Matches the end of a line or string. 
$string1 = "Hello World\n";
if ($string1 =~ m/rld$/) {
  print "$string1 is a line or string ";
  print "that ends with 'rld'.\n";
}

Output: 

Hello World
 is a line or string that ends with 'rld'.
\A Matches the beginning of a string (but not an internal line). 
$string1 = "Hello\nWorld\n";
if ($string1 =~ m/\AH/) {
  print "$string1 is a string ";
  print "that starts with 'H'.\n";
}

Output: 

Hello
World
 is a string that starts with 'H'.
\z Matches the end of a string (but not an internal line).[65] 
$string1 = "Hello\nWorld\n";
if ($string1 =~ m/d\n\z/) {
  print "$string1 is a string ";
  print "that ends with 'd\\n'.\n";
}

Output: 

Hello
World
 is a string that ends with 'd\n'.
[^…] Matches every character except the ones inside brackets. 
$string1 = "Hello World\n";
if ($string1 =~ m/[^abc]/) {
 print "$string1 contains a character other than ";
 print "a, b, and c.\n";
}

Output: 

Hello World
 contains a character other than a, b, and c.