"--passphrase-fd n" not working

[pd]

Here is what the man doc says about passing in the passphrase.

Read the passphrase from file descriptor  n.  If you  use  0  for  n, the=20
passphrase will be read from stdin. This can only be  used if  only=20
one  passphrase  is  supplied.  Don't use this option if you can avoid it.

I can't get it to work.  When I put in a filename it says it is looking for=
=20
file descriptor 0.  Is the file descriptor here something different than=20
the filename?  I tried inode number and that doesn't seem to work either.

Does it have to do with:

        --enable-special-filenames
		 This  options	enables a mode in which filenames
		 of the form -&n, where n is a non-negative deci=AD
		 mal  number,  refer to the file descriptor n and
		 not to a file with that name.

I don't understand the format being explained here:  "-&n".  I tried to=20
create a file with "&1" as the name and linux didn't like it.

Is there any other way to automate entry of the passphrase?

Thank you,

Paul