popen

Opens process file pointer

&reftitle.description; ``resource``false```popen` `string` `command` `string` `mode`

Opens a pipe to a process executed by forking the command given by `command`.

&reftitle.parameters;

`command`

- The command

`mode`

- The mode. Either `'r'` for reading, or `'w'` for writing.

  On Windows, `popen` defaults to text mode, i.e. any `\n` characters written to or read from the pipe will be translated to `\r\n`. If this is not desired, binary mode can be enforced by setting `mode` to `'rb'` and `'wb'`, respectively.

&reftitle.returnvalues;

Returns a file pointer identical to that returned by `fopen`, except that it is unidirectional (may only be used for reading or writing) and must be closed with `pclose`. This pointer may be used with `fgets`, `fgetss`, and `fwrite`. When the mode is 'r', the returned file pointer equals to the STDOUT of the command, when the mode is 'w', the returned file pointer equals to the STDIN of the command.

If an error occurs, returns &false;.

&reftitle.examples;

### `popen` example

    <?php
    $handle = popen("/bin/ls", "r");
    ?>

If the command to be executed could not be found, a valid resource is returned. This may seem odd, but makes sense; it allows you to access any error message returned by the shell:

### `popen` example

    <?php
    error_reporting(E_ALL);

    /* Add redirection so we can get stderr. */
    $handle = popen('/path/to/executable 2>&1', 'r');
    echo "'$handle'; " . gettype($handle) . "\n";
    $read = fread($handle, 2096);
    echo $read;
    pclose($handle);
    ?>

&reftitle.notes;

If you're looking for bi-directional support (two-way), use `proc_open`.

&reftitle.seealso;

- `pclose`
- `fopen`
- `proc_open`