Expect command with PGP.

rivacom · 08-16-2010, 02:06 PM

So I'm trying to make a simple enough script that does pgp decrypting for us and exports it for use.

Problem being, I run into the issue where the secret key needs to be entered when I run the gpg command. So I am trying to get the expect command to output the secret key. So below is my code, maybe someone can help figure it out. It basically doesn't do anything and it waits for someone to enter the key manually.

Code:

#! /bin/bash
#PGP Decryption Bash Script
clear
d=`date +%Y%m%d`
expect "*?passphrase:*"
send -- "password\r"
gpg -d file.txt.pgp > file_$d.txt
echo "file extracted"
exit

TB0ne · 08-16-2010, 02:48 PM

Quote:

Originally Posted by rivacom

So I'm trying to make a simple enough script that does pgp decrypting for us and exports it for use.

Problem being, I run into the issue where the secret key needs to be entered when I run the gpg command. So I am trying to get the expect command to output the secret key. So below is my code, maybe someone can help figure it out. It basically doesn't do anything and it waits for someone to enter the key manually.

Code:

#! /bin/bash
#PGP Decryption Bash Script
clear
d=`date +%Y%m%d`
expect "*?passphrase:*"
send -- "password\r"
gpg -d file.txt.pgp > file_$d.txt
echo "file extracted"
exit

Right...because the thing that generates the expect conditon (the gpg command), is BELOW the expect. Move it above.

jlinkels · 08-16-2010, 08:45 PM

I might be wrong, but this is using the expect command and send command in a bash script.

AFAIK expect is a TCL extension so you'd have to write your expect script in Expect, not in bash.

http://www.tcl.tk/man/expect5.31/index.html

jlinkels

rivacom · 08-17-2010, 08:18 AM

I've tried putting expect above and below with no luck. Jlinkels, is there a easier way to do it? Be nice to keep everything in bash without learning and putting in another set of programs.

jlinkels · 08-17-2010, 09:50 AM

Maybe you are trying to do something the hard way which is really easy.

You see, expect is used when you start another program (like telnet), and you expect something from that external program like username:. The instead of you as human user enter this information, you let expect send the information from your script to the external program (like telnet).

If I understand right, what you want to do is to prompt the user for a passphrase, read that passphrase from the user and run pgp with that information?

That would be something like this:

Code:

#!/bin/sh
echo -n "enter passphrase"
read pf
gpg --passphrase $pf -d file.txt.pgp > file_$d.txt

Please also refer to the Advanced Bash Scripting Guide, the link is in my signature.

Now take into account that I don't know exactly how to use gpg. If you want to start the gpg program from within your script, have gpg ask for a passphrase and let your scrip supply it, that is exactly how I described that in the second paragraph. You'd have to use expect.

jlinkels