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I have a bash+expect script which has to connect via ssh to the remote comp, read the file there, find specific line with the "hostname" (like "hostname aaaa1111") and store this hostname into the variable to be used after while. How can i get the value of the "hostname" parameter? I thought that line content will be in $expect_out(buffer) variable (so i can scan it and analyze), but it's not. My script is:

 #!/bin/bash ----bash part---- /usr/bin/expect << ENDOFEXPECT spawn bash -c "ssh root@$IP" expect "password:" send "xxxx\r" expect ":~#" send "cat /etc/rc.d/rc.local |grep hostname \n" expect ":~#" set line $expect_out(buffer) puts "line = $line, expect_out(buffer) = $expect_out(buffer)" ...more script... ENDOFEXPECT

Here http://en.wikipedia.org/wiki/Expect there is an example:

 # Send the prebuilt command, and then wait for another shell prompt. send "$my_command\r" expect "%" # Capture the results of the command into a variable. This can be displayed, or written to disk. set results $expect_out(buffer)

seems that it doesn't work in this case, or what's wrong with the script?

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  • Michael is right. However, the answer to the expect question is: you need \r instead of \n in your send command. Commented Aug 11, 2011 at 20:21
  • I need to use password identification in this script (for some reasons), and expect looks just right for this. And i've tried \r and \n in send command, anyway when i try to see line variable, i see only this: line = , expect_out(buffer) = (buffer) variable is not assigned by any conversion specifiers while executing ... What is the right way to get the line from the file into the variable? Commented Aug 12, 2011 at 16:09
  • Or it might be a way to open and read and scan the file on the remote comp using expect itself, without "send"? Commented Aug 12, 2011 at 16:45
  • No, because expect is running on your local machine, so you have to "send" the commands to the ssh process. Commented Aug 12, 2011 at 17:52

2 Answers 2

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First thing, your heredoc acts like a double quoted string, so the $expect_out variable is being substituted by the shell before expect starts. You need to ensure your heredoc is not being touched by the shell. Therefore, any shell variables need to be fetched in a different way. Here, I'm assuming IP is a shell variable, and I'm passing it through the environment.

export IP /usr/bin/expect << 'ENDOFEXPECT' set prompt ":~#" spawn ssh root@$env(IP) expect "password:" send "xxxx\r" expect $prompt send "grep hostname /etc/rc.d/rc.local \n" expect $prompt set line $expect_out(buffer) ...more script... ENDOFEXPECT
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  • Thanks glenn. IP is a variable defined in the "bash part", it's an argument to the script actually. I re-wrote this part, but still output is: expect_out = (buffer) grep hostname /etc/rc.d/rc.local hostname aaa1111 :~# line = , expect_out(buffer) = (buffer) etc Commented Aug 12, 2011 at 18:14
  • Ok, even if i change it so that all expect part is now a separate script (called by the bash script), still i can't get what i want. The script goes like this: send "grep hostname /etc/rc.d/rc.local \r" expect $prt set line $expect_out(buffer) puts "line = $line, expect_out(buffer)=$expect_out(buffer), expect_out(0,string)=$expect_out(0,string)", and the output (sirprisingly to me) is now: expect_out(buffer)= grep hostname /etc/rc.d/rc.local Commented Aug 12, 2011 at 18:27
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Why are you using expect for this?

ssh -i ssh_private_key root@${IP} "grep -E -o 'hostname.*$' /etc/rc.d/rc.local"
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  • and if you want the output in a variable, theoutput=$(allthatstuff) Commented Aug 11, 2011 at 20:35
  • I need to use password identification in this script (for some reasons), and can't exchange keys for this script Commented Aug 12, 2011 at 16:46

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