Perl – Matching patterns, conditional expressions

I’ve found the below mentioned information from different websites using Google. It is convenient to have all necessary information at one place, and that’s what I’ve done. I don’t take credit for anything written below.

Matching Pattern

Code                   Meaning
----                   ----------------------------
\w                     Alphanumeric Characters
\W                     Non-Alphanumeric Characters
\s                     White Space
\S                     Non-White Space
\d                     Digits
\D                     Non-Digits
\b                     Word Boundary
\B                     Non-Word Boundary
\A or ^                At the Beginning of a String
\Z or $                At the End of a String
.                      Match Any Single Character
*                      Zero or More Occurrences
?                      Zero or One Occurrence
+                      One or More Occurrences
{ n }                  Exactly N Occurrences
{ n,m }                Between N and M Occurrences
.* <pattern>           Less restrictive search, matches up to the last pattern
.*? <pattern>          Restrictive search, matches up the first pattern 
[ set_of_pattern ]     Match Any pattern from within the set
[ ^ set_of_pattern ]   Negates the match - does Not match any pattern Anything from the Set

Conditional Expressions

-A OPERAND Returns the access age of OPERAND when the program started.
-b OPERAND Tests if OPERAND is a block device.
-B OPERAND Tests if OPERAND is a binary file. If OPERAND is a file handle, then the current buffer is examined, instead of the file itself.
-c OPERAND Tests if OPERAND is a character device.
-C OPERAND Returns the inode change age of OPERAND when the program started.
-d OPERAND Tests if OPERAND is a directory.
-e OPERAND Tests if OPERAND exists.
-f OPERAND Tests if OPERAND is a regular file as opposed to a directory, symbolic link or other type of file.
-g OPERAND Tests if OPERAND has the setgid bit set.
-k OPERAND Tests if OPERAND has the sticky bit set.
-l OPERAND Tests if OPERAND is a symbolic link. Under DOS, this operator always will return false.
-M OPERAND Returns the age of OPERAND in days when the program started.
-o OPERAND Tests if OPERAND is owned by the effective uid. Under DOS, it always returns true.
-O OPERAND Tests if OPERAND is owned by the read uid/gid. Under DOS, it always returns true.
-p OPERAND Tests if OPERAND is a named pipe.
-r OPERAND Tests if OPERAND can be read from.
-R OPERAND Tests if OPERAND can be read from by the real uid/gid. Under DOS, it is identical to -r.
-s OPERAND Returns the size of OPERAND in bytes. Therefore, it returns true if OPERAND is non-zero.
-S OPERAND Tests if OPERAND is a socket.
-t OPERAND Tests if OPERAND is opened to a tty.
-T OPERAND Tests if OPERAND is a text file. If OPERAND is a file handle, then the current buffer is examined, instead of the file itself.
-u OPERAND Tests if OPERAND has the setuid bit set.
-w OPERAND Tests if OPERAND can be written to.
-W OPERAND Tests if OPERAND can be written to by the real uid/gid. Under DOS, it is identical to -w.
-x OPERAND Tests if OPERAND can be executed.
-X OPERAND Tests if OPERAND can be executed by the real uid/gid. Under DOS, it is identical to -x.
-z OPERAND Tests if OPERAND size is zero.

String Operator V/S Numerical Operator with example
eq  == ($a == $b  $a and $b are equal)
ne  != ($a != $b  $a is not equal to $b)
gt  >  ($a > $b  $a is greater than $b)
lt  <  ($a < $b  $a is lesser than $b)
ge  >= ($a >= $b  $a is greater or equal to $b)
le  <= ($a <= $b  $a is lesser or equal to $b)