PHP Filesystem is_writeable() Function

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The PHP Filesystem is_writeable() function is used to check whether the given file is writable or not. This function can return true if the file is writable. The filename argument can be a directory name that allows us to check if the directory is writable.

It has similar functionality as is_writable() function.

Syntax

Below is the syntax of the PHP Filesystem is_writeable() function −

bool is_writeable ($filename)

Parameters

Below is the only required parameter of the is_writeable() function −

Return Value

The function returns TRUE if the file is writable or FALSE if it is not writeable.

PHP Version

The is_writeable() function was first introduced as part of core PHP 4 and work well with the PHP 5, PHP 7 and PHP 8.

Example

Let us say we have a file called sample.txt in our current working directory or folder. So we will see how the PHP Filesystem is_writeable() function can be used to check that our file is writable or not.

<?php
    $file = "/PhpProject/sample.txt";
    if(is_writeable($file)) {
        echo ("The $file is writable");
    } else {
        echo ("The $file is not writable");
    }
?> 

Output

This will produce the following result −

The /PhpProject/sample.txt is writable

Example

Here is another basic demonstration to see how the is_writeable() function work to check that the given directory is writeable or not.

<?php
    // Mention directory path here
    $directory = 'Uploads';

    if (is_writeable($directory)) {
        echo "The directory is writeable.";
    } else {
        echo "The directory is not writeable.";
    }
?>

Output

Here is the outcome of the following code −

The directory is writeable.

Example

In this PHP code, we will use is_writeable() function and check that the non-existent file is writable or not.

<?php
    // Non-existent file path here 
    $filename = 'nonexistent.txt';

    if (is_writeable($filename)) {
        echo "The file is writeable.";
    } else {
        echo "The file is not writeable or it is not present.";
    }
?> 

Output

This will generate the below result −

The file is not writeable or it is not present

Example

In this PHP code, we will use is_writeable() function and check that the file is writable or not which has restricted permissions.

<?php
    // File has restricted permissions
    $filename = '/etc/passwd'; 

    if (is_writeable($filename)) {
        echo "The file is writeable.";
    } else {
        echo "The file is not writeable since it has restricted permissions.";
    }
?> 

Output

This will generate the below result −

The file is not writeable since it has restricted permissions.

Note

Permissions or authorization of the file or directory tells us that it is writeable. Make sure that the file permissions are properly set.

Summary

The is_writeable() method is a built-in function to check that the given file is writable or not. And it is useful when you have to check write permissions before trying to write to a file or directory. So basically you can prevent errors in your code.