`<io.h>`

`_close, close`	Closes a file.
`_read, _dos_read`	Reads from file.
`_write`	Writes to a file.
`access`	Determines accessibility of a file.
`chsize`	Changes the file size.
`dup`	Duplicates a file handle.
`dup2`	Duplicates a file handle (oldhandle) onto an existing file handle (nezvhandle).
`eof`	Checks for end-of-file.
`filelength`	Gets file size in bytes.
`getftime, setftime`	Gets and set the file date and time.
`ioctl`	Controls I/O device.
`isatty`	Checks for device type.
`lock`	Sets file-sharing locks.
`locking`	Sets or resets file-sharing locks.
`lseek`	Moves file pointer.
`read`	Reads from file.
`tell`	Gets the current position of a file pointer.
`umask`	Sets file read/write permission mask.
`unlink`	Deletes a file.
`unlock`	Releases file-sharing locks.
`write`	Writes to a file.