File And Directory Manipulation In PHP (part 1) - A Matter Of Existence (
Page 6 of 9 )
PHP also comes with a bunch of functions that allow you to test the status of
a file - for example, find out whether it exists, whether it's empty, whether
it's readable or writable, and whether it's a binary or text file. Of these, the
most commonly used operator is the file_exists() function, which is used to test
for the existence of a specific file.
Here's an example which asks the user to enter the path to a file in a Web
form, and then returns a message displaying whether or not the file exists:
<html>
<head>
</head>
<body>
<?php
// if form has not yet been submitted
// display input box
if (!$_POST['file'])
{
?>
<form action="<?=$_SERVER['PHP_SELF']?>" method="post">
Enter file path <input type="text" name="file">
</form>
<?
}
// else process form input
else
{
// check if file exists
// display appropriate message
if (file_exists($_POST['file']))
{
echo "File exists!";
}
else
{
echo "File does not exist!";
}
}
?>
</body>
</html>
There are many more such functions - here's a brief list, together with an
example that builds on the one above to provide more information on the file
specified by the user.
is_dir() - returns a Boolean indicating whether the specified path is a
directory
is_file() - returns a Boolean indicating whether the specified file is a
regular file
is_link() - returns a Boolean indicating whether the specified file is a
symbolic link
is_executable() - returns a Boolean indicating whether the specified file is
executable
is_readable() - returns a Boolean indicating whether the specified file is
readable
is_writable() - returns a Boolean indicating whether the specified file is
writable
And here's a script that demonstrates how you could use these operators to
obtain information on any file on your system:
<html>
<head>
</head>
<body>
<?php
// if form has not yet been submitted
// display input box
if (!$_POST['file'])
{
?>
<form action="<?=$_SERVER['PHP_SELF']?>" method="post">
Enter file path <input type="text" name="file">
</form>
<?
}
// else process form input
else
{
$output = "Filename: <b>" . $_POST['file'] . "</b><br>";
// check if file exists
// display appropriate message
if (file_exists($_POST['file']))
{
// is it a directory?
if (is_dir($_POST['file']))
{
$output .= "File is a directory <br>";
}
// is it a file?
if (is_file($_POST['file']))
{
$output .= "File is a regular file <br>";
}
// is it a link?
if (is_link($_POST['file']))
{
$output .= "File is a symbolic link <br>";
}
// is it executable?
if (is_executable($_POST['file']))
{
$output .= "File is executable <br>";
}
// is it readable?
if (is_readable($_POST['file']))
{
$output .= "File is readable <br>";
}
// is it writable?
if (is_writable($_POST['file']))
{
$output .= "File is writable <br>";
}
}
else
{
$output .= "File does not exist! <br>";
}
echo $output;
}
?>
</body>
</html>
And here's what the output might look like:
Filename: /home/me/addresses.dat
File is a regular file
File
is executable
File is readable
File is writable
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