expect

hk_linux · 02-07-2005, 05:51 AM

hi,
I want to rsync files into a backup server periodically. I use rsync over ssh. I use ssh-keygen to generate public-private keypair (using a passphrase) and copy the public key to the destination machine.
Now when i do ssh, the rsync prompts for the passphrase. To supply it, i use the expect script. I am new to expect. I googled and found the following script.

<code>
#!/usr/bin/expect
set timeout 19900
spawn /bin/bash
expect -re "]# "
send "rsync -avz -e ssh user@host:/etc/passwd /tmp/\r"
expect -re "Enter passphrase"
sleep 2
send "abcdefgh\r"
expect -re "total size is"
send "exit\r"
</code>

The passphrase is "abcdefgh". This works perfectly fine. But my requirement is to get this passphrase from a file instead of hardcoding inside the expect script like the following.

<code>
expect -re "Enter passphrase"
sleep 2
send "`cat /tmp/passphrasefile`\r"
</code>

How can i do this.

Any help is appreciated. TIA.

Eduardo Nunes · 09-03-2010, 10:46 AM

Hi hk_linux,

As you I ran into the same problem and found out the answer checking the TCL/TK manual.

You have to open the file you want to `cat` with TCL commands (not shell one's) and place its contents on a variable. Then you might use this variable anytime at your script. At last, you may close the file descriptor.

For example:

Code:

set fp [open "/tmp/passphrasefile" r]
set data [read $fp]

expect "somestuff"
send -- "$data"

close $fp

Or you may use all macros in one line, like:

Code:

expect "somestuff"
send -- "[read [open "/tmp/passphrasefile" r]]"

Altought this thread is old this may help anyone that finds it, like me again!

Good luck,

Eduardo Nunes

HadroLepton · 03-01-2018, 02:34 AM

(wow. it is 2018 and i found an answer outside of stackoverflow.com)

for the people coming here looking for how to read both username and password from file

Code:

#!/usr/bin/expect -f

set passfile [open "~/.secrets/logindata" r]
gets $passfile username
gets $passfile password
close $passfile

spawn somelogintool
expect "username:"
send "$username\r"
expect "password:"
send -- "$password\r"
expect eof

set exitstatus [lindex [wait] 3]
puts "exitstatus: $exitstatus"
exit $exitstatus

bonus: the last three lines is how to print the exit status of somelogintool

the file logindata should look like this

Code:

username
password

that is: two lines. first line containing username followed by newline. second line containing password followed by newline. anything else is possible but will make the reading code more complicated.