dio_open

Opens a file (creating it if necessary) at a lower level than the C library input/ouput stream functions allow.

&reftitle.description; `resource` `dio_open` `string` `filename` `int` `flags` `int` `mode` 0

`dio_open` opens a file and returns a new file descriptor for it.

&reftitle.parameters;

`filename`

- The pathname of the file to open.

`flags`

- The `flags` parameter is a bitwise-ORed value comprising flags from the following list. This value must include one of `O_RDONLY`, `O_WRONLY`, or `O_RDWR`. Additionally, it may include any combination of the other flags from this list.

  - `O_RDONLY` - opens the file for read access.

  - `O_WRONLY` - opens the file for write access.

  - `O_RDWR` - opens the file for both reading and writing.

  - `O_CREAT` - creates the file, if it doesn't already exist.

  - `O_EXCL` - if both `O_CREAT` and `O_EXCL` are set and the file already exists, causes `dio_open` to fail.

  - `O_TRUNC` - if the file exists and is opened for write access, the file will be truncated to zero length.

  - `O_APPEND` - write operations write data at the end of the file.

  - `O_NONBLOCK` - sets non blocking mode.

  - `O_NOCTTY` - prevent the OS from assigning the opened file as the process's controlling terminal when opening a TTY device file.

`mode`

- If `flags` contains `O_CREAT`, `mode` will set the permissions of the file (creation permissions). `Mode` is required for correct operation when `O_CREAT` is specified in `mode` and is ignored otherwise.

  The actual permissions assigned to the created file will be affected by the process's umask setting as per usual.

&reftitle.returnvalues;

A file descriptor or &false; on error.

&reftitle.examples;

### Opening a file descriptor

    <?php

    $fd = dio_open('/dev/ttyS0', O_RDWR | O_NOCTTY | O_NONBLOCK);

    dio_close($fd);
    ?>

&reftitle.seealso;

- `dio_close`