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Old 02-27-2013, 02:15 PM   #1
Registered: Sep 2007
Location: San Diego, CA
Posts: 222

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OSX bash & expect

I have a script that must perform a 'sudo' operation on each of a number of hosts. I'm trying to get expect working so I only have to enter it once, and have run into a couple of issues.

First, several examples suggest to use:

/usr/bin/expect <<EOD
spawn ssh -t $host /usr/bin/sudo -v
expect "Password:"
send "$SUDOPASS\n"
However, as soon as I enter the second '<', all of the quoting gets screwed up, and my script will terminate with an unexpected end of file. This is really strange, as I use the same mechanism with cat to write out files in other scripts.

Other examples suggest:

/usr/bin/expect -c "
spawn ssh -t $host /usr/bin/sudo -v
expect "Password:"
send "$SUDOPASS\n"
Doing it this way (and adding -d to expect), I get errors about no tty and a repeat of my password with an 'n' appended to the end, so it isn't sending a newline (I've tried '\r' as well), but instead appears to be escaping the 'n'

Since most of the examples I'm finding are from Linux, I expect (ha, ha, pun not intended!) that they're using a GNU expect, and I'm using a BSD expect. I am reading through the man page, but the word "spawn" appears so many times, it could be quite a while before I stumble across the correct instance.

Here's a result that seems to be closest to working:

flamingo:~ jnojr$ Scripts/ 
Assuming you have one 'sudo' password for all of your hosts, enter it now: 
expect version 5.45
spawn /usr/bin/ssh -t macbook /usr/bin/sudo -v
parent: waiting for sync byte
parent: telling child to go ahead
parent: now unsynchronized from child
spawn: returns {67358}

expect: does "" (spawn_id exp7) match glob pattern "Password:"? no
expect: does "Password:" (spawn_id exp7) match glob pattern "Password:"? yes
expect: set expect_out(0,string) "Password:"
expect: set expect_out(spawn_id) "exp7"
expect: set expect_out(buffer) "Password:"
send: sending "password\n" to { exp7 }
argv[0] = /usr/bin/expect  argv[1] = -d  argv[2] = -c  argv[3] = 
    spawn /usr/bin/ssh -t macbook /usr/bin/sudo -v
    expect Password: { send password\n }  
set argc 0
set argv0 "/usr/bin/expect"
set argv ""
sudo: no tty present and no askpass program specified
That's with leaving the '\n' outside of the quotes, as in
send "$SUDOPASS"\n
It seems to be mostly working, except skipping the '-t' option to ssh


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