Signing Files with PGP

Hello List, I try to setup a script which automatically signs a file with PGP. With the system command this looks like that: % /usr/local/bin/pgps -u Juergen -ato test1.sig ~/test1.txt A private key is required to make a signature. Need a pass phrase to decrypt private key: 1024 bits, Key ID F593ED45, Created 2001-12-14 "Juergen Mueller <j.mueller@pro.vider.de>" Enter pass phrase: Pass phrase is good. Creating output file test1.sig % Now the thing is how can I implement the pass phrase into PHP so that the command is being done? When I use something like $command="/usr/local/bin/pgps -u Juergen -ato test1.sig ~/test1.txt"; exec("$command",$answer); obviously nothing is happening cause the pass phrase was not given. Thanks. Juergen