Relative path not working in cron PHP script

If a PHP script is run as a cron script, the includes often fail if relative paths are used. For example, if you have

require_once('foo.php');

the file foo.php will be found when run on the command line, but not when run from a cron script.

A typical workaround for this is to first chdir to the working directory, or use absolute paths. I would like to know, however, what is different between cron and shell that causes this behavior. Why does it fail when using relative paths in a cron script?

Change the working directory to the running file path. Just use

chdir(dirname(__FILE__));
include_once '../your_file_name.php'; //we can use relative path after changing directory

in the running file. Then you won't need to change all the relative paths to absolute paths in every page.

The working directory of the script may be different when run from a cron. Additionaly, there was some confusion about PHPs require() and include(), which caused confusion about the working directory really being the problem:

include('foo.php') // searches for foo.php in the same directory as the current script
include('./foo.php') // searches for foo.php in the current working directory
include('foo/bar.php') // searches for foo/bar.php, relative to the directory of the current script
include('../bar.php') // searches for bar.php, in the parent directory of the current working directory

The only chance I got "require_once" to work with cron and apache at the same time was

require_once(dirname(__FILE__) . '/../setup.php');

Because the "current working directory" for cron jobs will be the directory where your crontab file exists -- so any relative paths with be relative to THAT directory.

The simplest way to handle that is with dirname() function and PHP __FILE__ constant. Otherwise, you will need to edit the file with new absolute paths whenever you move the file to a different directory or a server with a different file structure.

dirname( __FILE__ )

__FILE__ is a constant defined by PHP as the full path to the file from which it is called. Even if the file is included, __FILE__ will ALWAYS refer to the full path of the file itself -- not the file doing the including.

So dirname( __FILE__ ) returns the full directory path to the directory containing the file -- no matter where it is included from and basename( __FILE__ ) returns the file name itself.

example: Let's pretend "/home/user/public_html/index.php" includes "/home/user/public_html/your_directory/your_php_file.php".

If you call dirname( __FILE__ ) in "your_php_file.php" you would get "/home/user/public_html/your_directory" returned even though the active script is in "/home/user/public_html" (note the absence of the trailing slash).

If you need the directory of the INCLUDING file use: dirname( $_SERVER['PHP_SELF'] ) which will return "/home/user/public_html" and is the same as calling dirname( __FILE__ ) in the "index.php" file since the relative paths are the same.

example usages:

@include dirname( __FILE__ ) . '/your_include_directory/your_include_file.php';

@require dirname( __FILE__ ) . '/../your_include_directory/your_include_file.php';

Another possibility is that the CLI version is using a different php.ini file. (By default, it'll use php-cli.ini and fallback to the standard php.ini)

Also, if you're using .htaccess files to set your library path, etc. this obviously won't work via the cli.

In addition to the accepted answer above, you can also use:

chdir(__DIR__);

When executed trough a cron job your PHP script probably runs in different context than if you start it manually from the shell. So your relative paths are not pointing to the right path.

The DIR works although it will not work on my localhost as it has a different path than my live site server. I used this to fix it.

    if(__DIR__ != '/home/absolute/path/to/current/directory'){ // path for your live server
        require_once '/relative/path/to/file';
    }else{
        require_once '/absolute/path/to/file';
    }