Script to execute command to get info from multiple servers

isourabh.wadhwa · 05-17-2012, 08:49 AM

I dont have password-less authentication and no one will allow me ti set it up.

We are okay with specifying passwords in script.

I dont have root login but can do everything using sudo.

I want o/p of "df -h" and "hostname" from a list of servers to a file present on the server on which I'll make the script.

to summarise:
I have one server named "Host" and 100 servers "node1/2/3...100"

i want o/p of "df -h" and "hostname" of "node1/2/3...100" in a file "/home/user1/data.log" on server "Host"

P.s. I dont want this to happen to every server in list parallely, sequentialy accessing these servers will do the work for me

Ser Olmy · 05-17-2012, 10:29 AM

I would use a simple script to loop through the list of servers, and an expect script to do the actual logon and run the commands.

The logic of the script would look something like this:

for every $entry in servers.list
do
call the expect script with $entry as an argument, perhaps also a username and a password, redirect output to a logfile
done

Here's an implementation of the above as a bash script:

Code:

#!/bin/bash

set login=user
set password=MyPassword
set server_list=./servers.lst
set expect_script=./my_expect_script
set logfile=./data.log

cat $server_list | while read $servername ; do
  expect $expect_script $servername $login $password >> $logfile
done

This is a rough draft and completely untested. At the very least, you would want to add some lines to the log file before and after calling the expect script to indicate which server the information is coming from.

As for the expect script, the logic of that could be something like this:

- grab server name and login details from the command line arguments
- suppress output
- connect to the server with ssh
- wait for the password prompt
- send the password
- wait for the shell prompt
- enable output
- send "sudo df -h"
- wait for the shell prompt
- send "sudo hostname"
- wait for the shell prompt
- suppress output
- send "logout"

Here's an implementation of the above (not guaranteed to be bug free):

Code:

set hostname [lindex $argv 0]
set login [lindex $argv 1]
set password [lindex $argv 2]
set timeout 20

log_user 0
spawn ssh $login@$hostname
expect "password:" {
  send "$password\r"
}
expect "~$" {
  log_user 1
  send "sudo df -h\r"
}
expect "~$" {
  send "sudo hostname\r"
}
log_user 0
send "logout\r"