Shell Programming and Scripting

       --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.

> cat pass
s3cr3t
> gpg --batch --no-tty --armor --passphrase-file pass --symmetric test.file
> ls test.*
test.file  test.file.asc
> file test.file.asc
test.file.asc: PGP armored data message

> cat pass    # Run the 'cat' program to show the contents of file 'pass' which
              # contains the passphrase
s3cr3t        # Contents of file 'pass'
# Calling gpg in batch mode, telling it not to allocate a TTY, asking for
# ASCII-Armor output (non-binary data), providing the passphrase in file 'pass',
# symmetric enryption for file 'test.file'
> gpg --batch --no-tty --armor --passphrase-file pass --symmetric test.file
> ls test.*   # Display a listing of the original & encypted file
test.file  test.file.asc
> file test.file.asc # Run the 'file' utility to take a guess at the type of the
                     # content of file 'test.file.asc'
test.file.asc: PGP armored data message # It tells us that it's encrypted,
                                        # armored data