File Descriptor File System

The File Descriptor File System (FDFS) allows applications to reference a process's open file descriptors (0, 1, 2, 3, and so forth) as if they were files in the UNIX File System (for example, /dev/fd/0, /dev/fd/1, /dev/fd/2) by aliasing a process's open file descriptors to file objects. When the FDFS is mounted, opening or creating a file descriptor file has the same effect as calling the dup(2) system call.

The FDFS allows applications that were not written with support for UNIX I/O to avail themselves of pipes, named pipes, and I/O redirection.

The FDFS is not mounted by default and must either be mounted by hand or by an entry placed in the /etc/fstab file.

For more information on the FDFS, see the fd(4) reference page.