PHP is_executable Function
last modified April 3, 2025
The PHP is_executable function checks if a file is executable. It
verifies both file permissions and existence before returning a boolean result.
Basic Definition
The is_executable function determines if the specified file is
executable. It checks both the file's existence and its executable permission.
Syntax: is_executable(string $filename): bool. Returns true if the
file exists and is executable, false otherwise. Works on both Unix and Windows.
Basic is_executable Example
This shows the simplest usage of is_executable to check a file.
<?php declare(strict_types=1); $file = "/usr/bin/php"; $isExecutable = is_executable($file); echo $isExecutable ? "File is executable" : "File is not executable";
This checks if PHP binary is executable. The result depends on your system's permissions. On most systems, this will return true for the PHP binary.
Checking Script File
We can verify if a PHP script itself has executable permissions.
<?php
declare(strict_types=1);
$script = __FILE__;
$isExecutable = is_executable($script);
if ($isExecutable) {
echo "This script has executable permissions";
} else {
echo "This script is not executable";
}
This checks the current script's executability. Note that PHP scripts typically don't need executable flags since they're executed by the PHP interpreter.
Windows Executable Check
On Windows, is_executable checks file extensions in PATHEXT.
<?php declare(strict_types=1); $file = "C:\\Windows\\System32\\cmd.exe"; $isExecutable = is_executable($file); var_dump($isExecutable); // Outputs: bool(true)
This verifies if cmd.exe is executable. On Windows, it checks both file existence and whether the extension is in the system's PATHEXT environment.
Checking Directory
is_executable can also check if a directory is executable.
<?php declare(strict_types=1); $dir = "/tmp"; $isExecutable = is_executable($dir); echo $isExecutable ? "Directory is searchable" : "Directory is not searchable";
For directories, executable permission means the directory is searchable. This allows accessing files within the directory if read permissions are also set.
Relative Path Check
The function works with relative paths as well as absolute paths.
<?php
declare(strict_types=1);
$file = "./test.sh";
$isExecutable = is_executable($file);
if ($isExecutable) {
echo "The local test.sh script is executable";
} else {
echo "The script is not executable or doesn't exist";
}
This checks a shell script in the current directory. Remember that relative paths are resolved relative to the current working directory of the PHP process.
Edge Cases
is_executable has specific behaviors with special cases.
<?php declare(strict_types=1); $nonexistent = "/nonexistent/file"; $symlink = "/usr/bin/php"; // Assuming this is a symlink on your system var_dump(is_executable($nonexistent)); // bool(false) var_dump(is_executable($symlink)); // Follows symlink to target
For nonexistent files, it returns false. For symlinks, it follows to the target. The function also considers the effective user ID when checking permissions.
Best Practices
- Check existence first: Use file_exists before is_executable.
- Error handling: Consider using error suppression (@) in production.
- Security: Validate paths before checking permissions.
- Cross-platform: Be aware of Windows vs Unix differences.
- Caching: Results may be cached; use clearstatcache() if needed.
Source
PHP is_executable Documentation
This tutorial covered the PHP is_executable function with practical
examples showing its usage in different scenarios across operating systems.