Can't get expect to work. send will not display an output

edomingox · 07-10-2009, 04:48 AM

I'm trying to ssh into multiple servers and get data to display on the screen. I can ssh in just fine. But once I'm in, I can't seem to get anything to display using the send command. Here's the expect part when the prompt appears:

Code:

for {set x 50} {$x <= 55} {incr x} {
   log_user 0
   spawn -noecho ssh root@${network}.${x}
   
   expect {
      "assword:" {
          send "$pass\r"
      }
   }
   
   expect {
      "/]#" {
           log_user 1
           send_user "Localhost : "
           send "cat /etc/hosts | grep localhost"  ;# this is an example 
           send_user "\n"
           send "exit/r"
           expect eof
      }
      "Permission denied" {
          send_user "Incorrect password.\n"
          continue
      }
   }
}

so the main problem is no matter what command I try to place, it seems to skip it and just display the send_user stuff. Am I missing something to this? I just want to run simple things like cat or ls and display a result. Can anyone help?

acid_kewpie · 07-11-2009, 09:57 AM

well you never actually send a valid command. the cat has no return at the end - \r - and the exit has it wrong - /r. You managed it correctly on the password entry, why not elsewhere?

edomingox · 07-12-2009, 12:52 AM

Quote:

Originally Posted by acid_kewpie

well you never actually send a valid command. the cat has no return at the end - \r - and the exit has it wrong - /r. You managed it correctly on the password entry, why not elsewhere?

I don't know why it won't work. This is the first time (using expect) that I'm trying to do screen outputs like this. I've made password change script and a user creation script using expect. Those work fine because I know what I'm "expecting" (which is usually a prompt) and then I send the next command. Here it just doesn't seem to work for me. This is only the 3 script I've ever written in expect.

actually the /r was just a typo from copying it over. and i've included the \r at the end of the cat and it looks like it skips it and doesn't display the output of cat.

acid_kewpie · 07-12-2009, 04:32 AM

after you send something you need to do an expect to allow for it to wait for the output. so after *every* send, expect a prompt again.

edomingox · 07-12-2009, 11:44 PM

i've tried doing:

send "cat /etc/hosts | grep localhost\r"
expect "cat /etc/hosts | grep localhost\r"

and it displays results, but I get the "cat /etc/hosts | grep localhost\r" command echoed back still. I'm wondering if I'm missing certain options.

What about sending the results into a variable? How would I do that? That way, all I have to do is call a send_user "$variable" command.

acid_kewpie · 07-13-2009, 12:33 AM

no, that doesn't make sense. The whole point is that you need to expect something that will only be there after your command has completed, e.g. another bash prompt

send "ls\r"
expect "]$ "
send "cd /var/log\r"
expect "]$ "
send "tail messages\r"
expect "]$ "

and so on.

edomingox · 07-13-2009, 04:31 AM

I've done that but I get the command echoing. I would like something to this effect as an output:

Latest file in directory: hosts

And to get that output I would run something like this in a normal situation:

ls -ltr /etc | head -1 | cut -d" " -f3 (i'm not sure if the command is right but it's suppose to just grab the file name)

And to script it, I would do:

send_user "Latest file in directory: "
send "ls -ltr /etc | head -1 | cut -d" " -f3\r"

But if I did it this way, I get an echo of the command and it ruins the output.

Now, I tried doing this:

set $result [exec {ls -ltr /etc | head -1 | cut -d" " -f3}]
send_user "Latest file in directory: $result"

and that is the type of output I would want, BUT, that command is run on the server I'M on and not the server that I've expect ssh'd into.

I think I can do this if I figure out the spawned ID and assign the command to that ID but I don't see examples on how to do that.

I've written a password change script and a user name add/delete/reset password script and they work fine because I run commands right after a prompt and I do a log_user 0 so I don't need to see anything on screen. But what I'm trying to do here is just display information by ssh'ing into many machines.

edomingox · 07-14-2009, 12:04 AM

I've managed to find a command that helps. I found using "set temp [string trimright "ls -ltr /etc | head -1 | cut -d\" \" -f3\r] works to eliminate the echo.