FileSystem Function in PHP: Part 16

Introduction

In this article I describe the PHP FileSystem functions popen, readfile, readlink, realpath and rename. To learn some other FileSystem functions, go to:

  1. FileSystem Function in PHP: PART 1
  2. FileSystem Function in PHP: PART 2
  3. FileSystem Function in PHP: PART 3
  4. FileSystem Function in PHP: PART 4
  5. FileSystem Function in PHP: PART 5
  6. FileSystem Function in PHP: PART 6
  7. FileSystem Function in PHP: PART 7
  8. FileSystem Function in PHP: PART 8
  9. FileSystem Function in PHP: PART 9
  10. FileSystem Function in PHP: PART 10
  11. FileSystem Function in PHP: PART 11
  12. FileSystem Function in PHP: PART 12
  13. FileSystem Function in PHP: PART 13
  14. FileSystem Function in PHP: PART 14
  15. FileSystem Function in PHP: PART 15

PHP popen() Function

The PHP FileSystem popen function opens a process's file pointer; in other words it returns a file pointer, identical to that returned by fopen or returns false if an error occurs.

Syntax
popen(comman,mode)

Parameter in popen function

The parameters of the function are:
Parameter Description
command It specifies the command to execute.
mode It specifies the connection mode and the possible values are:
  • r: read only
  • w: write only.

Example

An example of the
function is:

<?
php
 $
file=popen('/bin/ls','r');
 pclose($file);

 ?>


PHP readfile() Function

The PHP FileSystem readfile function is used to read a file and places the data in a buffer and it returns the number of bytes read from the file or false if an error occurs.

Syntax
readfile(filename,includepath,context)

Parameter in popen function

The parameters of the function are:
Parameter Description
file It specifies the file to read.
includePath It is an optional parameter; it is is set to 1 (one) to search for the file in the include path.
context It specifies the context of the file handle.

Example

An example of the
function is:

<?
php
echo
readfile("test.txt");
?>

Output

read-file-function-in-php.jpg

PHP readlink() Function

The PHP FileSystem readfile function returns the target of a symbolic link or say this function returns the target on success or false on failure.

Syntax
readlink(linkPtah)

Parameter in readlink function

The parameter of the function is:
Parameter Description
linkPath It specifies the link path to check.

Example

An example of the
function is:

<?
php
echo
readlink("/wamp/test");
?>


PHP realpath() Function

The PHP FileSystem realpath function returns the absolute path name, in other words it returns the absolute pathname on success or returns false on failure.  

Syntax
realpath(path)

Parameter in realpath function

The parameter of the function is:
Parameter Description
path It specifies the path to check.

Example

An example of the
function is:

<?
php
echo
realpath("test.txt");
?>

Output

real-path-function-in-php.jpg

PHP reaname() Function

The PHP FileSystem rename function renames a file or directory and it returns true on success or false on failure.

Syntax
rename(oldname,newname,context)

Parameter in rename function

The parameter of the function is:
Parameter Description
oldname It specifies the file or directory to be renamed.
newname It specifies the new name of the file or directory .
context It specifies the context of the file handle.

Example

An example of the
function is:

<?
php
rename
("xyz.jpg","abc.jpg");
if
(file_exists("abc.jpg"))
{

echo
"File has been renamed";
}

else

{

echo
"File has not been renamed";
}
?>

Output

rename-function-in-php.jpg