LinuxQuestions.org
Review your favorite Linux distribution.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Newbie
User Name
Password
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!

Notices


Reply
  Search this Thread
Old 05-14-2015, 02:03 PM   #1
legendmac
LQ Newbie
 
Registered: Apr 2015
Location: AZ
Posts: 14

Rep: Reputation: Disabled
How to return from shell 'read' command passed in expect script?


I have a shell script that calls an expect script I wrote to ssh login to another host and get user input regarding that host's network configuration. I pass four arguments to the expect script: the remote host ip address, the username, the password, and the list of commands to run. My expect script is below:

#!/usr/bin/expect
# Usage: expectssh <host> <ssh user> <ssh password> <script>

set timeout 60
set prompt "(%|#|\\$) $"
set commands [lindex $argv 3];

spawn ssh [lindex $argv 1]@[lindex $argv 0]

expect {
"*assword:" {
send -- "[lindex $argv 2]\r"
expect -re "$prompt"
send -- "$commands\r"
}

"you sure you want to continue connecting" {
send -- "yes\r"
expect "*assword:"
send -- "[lindex $argv 2]\r"
expect -re "$prompt"
send -- "$commands\r"
}

timeout {
exit }

expect -re $prompt
send -- "exit\r"
}

The script runs well, except that if I send a command such as 'read' that requires user input, the script does not continue or exit after the user presses enter. It just hangs.

The commands I pass to the expect script and it's call are as follows:
SCRIPT='hostname > response.txt;netstat -rn;read net_card?"What is the network interface card number? " >> response.txt; read net_mask?"What is the subnet mask? " >> response.txt'

/usr/bin/expect ./expectssh.exp $hostip $usr $pswd "$SCRIPT"

Any suggestions on how I can pass a command to my expect script that requires user input without it hanging?

On a side note because I know it will come up - I am not allowed to do key-based automatic SSH login. I have to prompt for a username and password, which is done from my main shell script.

Thanks for any suggestions and help you can provide!
 
Old 05-14-2015, 02:17 PM   #2
schneidz
LQ Guru
 
Registered: May 2005
Location: boston, usa
Distribution: fc-15/ fc-20-live-usb/ aix
Posts: 5,026

Rep: Reputation: 845Reputation: 845Reputation: 845Reputation: 845Reputation: 845Reputation: 845Reputation: 845
seems like setting up ssh with keys is far simpler (and secure) than to kludge something together to bypass the password prompt.
 
Old 05-22-2015, 02:15 PM   #3
legendmac
LQ Newbie
 
Registered: Apr 2015
Location: AZ
Posts: 14

Original Poster
Rep: Reputation: Disabled
I was able to fix my problem. What was missing was an 'interact' command following the read statement so that it would wait for user input (implemented through an if statement). I also moved the commands to be run into a separate -re $prompt block within the expect command and just called exp_continue at the end of the "*assword:" and "you sure you want to continue connecting" conditions. The updated code is below if anyone is interested:

expect {
-re "(.*)assword:" {
send -s "[lindex $argv 2]\r"
exp_continue
}
"denied, please try again" {
send_user "Invalid password or account.\n"
exit 5
}
"incorrect" {
send_user "Invalid password or account.\n"
exit 5
}
"you sure you want to continue connecting" {
send -s "yes\r"
exp_continue
}
-re $prompt {
foreach cmd $commands {
send -- "$cmd\r"

if {[string first "read" "$cmd"] != -1} {
interact "\r" return
send -- "\r"
}
}
}
timeout {
send_user "Connection to host [lindex $argv 0] timed out."
exit 10
}
eof {
send_user "Connection to host failed."
exit
}
}
 
  


Reply

Tags
arguments, expect, shell scripting, ssh


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
bash script read command issue with carriage return itamarm Linux - General 3 06-17-2013 08:37 AM
Shell script using expect to login to couple of remote servers and read "crontab -l" jaipsharma Linux - Networking 3 03-16-2013 05:59 PM
Can expect return control of a spawned process to a shell script? duffrecords Programming 4 04-28-2010 03:33 PM
shell script reads all file names passed on the command line path_finder Linux - Kernel 1 04-01-2010 05:01 PM
exec the expect command in a shell script wanghao Linux - Networking 6 11-24-2007 12:06 AM


All times are GMT -5. The time now is 08:24 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration