mkfifo makes a FIFO special file with name pathname. mode
specifies the FIFO's permissions. It is modified by the process's umask
in the usual way: the permissions of the created file are
(mode & ~umask).
A FIFO special file is similar to a pipe, except that it is created in a
different way. Instead of being an anonymous communications channel, a FIFO
special file is entered into the file system by calling mkfifo.
Once you have created a FIFO special file in this way, any process can open it
for reading or writing, in the same way as an ordinary file. However, it has
to be open at both ends simultaneously before you can proceed to do any input
or output operations on it. Opening a FIFO for reading normally blocks until
some other process opens the same FIFO for writing, and vice versa. See
fifo(4) for non-blocking handling of FIFO special files.
One of the directories in pathname did not allow
search (execute) permission.
pathname already exists.
Either the total length of pathname is greater than
PATH_MAX, or an individual file name component has a length greater
than NAME_MAX. In the GNU system, there is no imposed limit on
overall file name length, but some file systems may place limits on the
length of a component.
A directory component in pathname does not exist or
is a dangling symbolic link.
The directory or filesystem has no room for the new
A component used as a directory in pathname is not,
in fact, a directory.