File Test Operators in PERL

File Test Operators in PERL:

                  Perl has many operators that you can use to test different aspects of a file. For example, you can use the -e operator to ensure that a file exists before deleting it. Or, you can check that a file can be written to before appending to it. By checking the feasibility of the impending file operation, you can reduce the number of errors that your program will encounter.

A complete list of the operators:

Operator	Description
-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 PERAND	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.

Note:
        If the OPERAND is not specified in the file test, the $ variable will be used instead.
Example:

 $filename = '/path/to/your/file.doc';
 $directoryname = '/path/to/your/directory';
 if (-f $filename) 

 {
     print "This is a file.";
 }
 if (-d $directoryname) 

 {
     print "This is a directory.";
 }