From the man page (which you have of course read) some options that might be helpful:
Code:
--batch
--no-batch
Use batch mode. Never ask, do not allow interactive commands.
--no-batch disables this option.
--no-tty
Make sure that the TTY (terminal) is never used for any output.
This option is needed in some cases because GnuPG sometimes
prints warnings to the TTY even if --batch is used.
--passphrase-fd n
Read the passphrase from file descriptor n. Only the first line
will be read from file descriptor n. If you use 0 for n, the
passphrase will be read from stdin. This can only be used if
only one passphrase is supplied. Note that this passphrase is
only used if the option --batch has also been given. This is
different from gpg.
--passphrase-file file
Read the passphrase from file file. Only the first line will be
read from file file. This can only be used if only one
passphrase is supplied. Obviously, a passphrase stored in a file
is of questionable security if other users can read this file.
Don't use this option if you can avoid it. Note that this
passphrase is only used if the option --batch has also been
given. This is different from gpg.
--passphrase string
Use string as the passphrase. This can only be used if only one
passphrase is supplied. Obviously, this is of very questionable
security on a multi-user system. Don't use this option if you
can avoid it. Note that this passphrase is only used if the
option --batch has also been given. This is different from gpg.
