How to use 'expect' to pass UID & Password to a "for loop" in shell script?
Friends,
Need someone's help in helping me with the below requirement for a script:
> For a list of servers(over 100+), I need to login into each of them(cannot configure password-less ssh) & grab few configuration details <
I know, this is possible through expect programming in a simple shell script, but unfortunately I'm not able to get one to work as required. Below is what I could manage to write without expected results:
Code:
cat server_list
server1
server2
server3
..
..
..
Code:
cat for_loop.sh
for i in `cat server_list`
do
multibos -S
done
Running the above written expect script doesn't solve my purpose - it does nothing Could someone help me rectify this script or help me with a better idea?
-- Souvik
Last edited by thisissouvik; 11-11-2013 at 09:56 AM..
Reason: Reorganizing!
Here's a very basic way using Expect that should hopefully set you on the path to what you want to accomplish:
Code:
#!/usr/bin/expect -f
#
#
# set credentials - NOT RECOMMENDED METHOD
set u "username"
set p "password"
# get host name from command-line
set h [lindex $argv 0]
# set the command to run
set cmd "date"
# spawn a connection to the host and
# run the given command
spawn ssh -t $u@$h $cmd
# handle the password prompt
expect "?assword:*"
send -- "$p\r"
send -- "\r"
# done
expect eof
I've found reading files using Expect to be a bit flaky, so you could use a while loop to parse your file with the hostnames and feed it to the Expect script like so:
while read hosts;do sendCmd $hosts;done < server_list
Output:
spawn ssh -t username@server1 date
username's Password:
Mon Nov 11 08:52:42 EST 2013
Connection to server1 closed.
75d6b64809eec8e415f7bca6b09b6f40
Last edited by in2nix4life; 11-12-2013 at 01:50 PM..
Your basic expect based script did the ground work for me - could login to any server passing the hostname to parameter "h", so this is how my little modified script looks now:
Code:
#!/usr/bin/expect -f
#
#
# set credentials
set u "msouvik"
set p "pass^123"
# get host name from command-line
# set h "my_desired_server"
# set the command to run
set cmd "echo Hello Souvik! >> /export/home/msouvik/echo.out"
# spawn a connection to the host and run the given command
spawn -noecho ssh -t $u@$h $cmd
# handle the password prompt
expect "?assword:*"
send -- "$p\r"
send -- "\r"
# done
expect eof
I could not manage to pass multiple server names to this expect script, the methods I tried --
1. Called this expect script from an external "for" & "while" loop -- got an obvious error of parameter "h" not found:
Code:
for h in `cat my_server_list`
do
<Path of above written expect script>
done
2. Added a "for" loop within the above expect script:
Code:
#!/usr/bin/expect -f
#
#
for h in `cat my_server_list`
do
# set credentials
set u "msouvik"
set p "pass^123"
# get host name from command-line
# set h ""
# set the command to run
set cmd "echo Hello Souvik! >> /export/home/msouvik/echo.out"
# spawn a connection to the host and run the given command
spawn -noecho ssh -t $u@$h $cmd
# handle the password prompt
expect "?assword:*"
send -- "$p\r"
send -- "\r"
# done
expect eof
done
That failed since it couldn't understand expect syntaxe(s) within the for loop.
Did you try the while loop that I listed in my last post? I mentioned that reading files inside of Expect is a bit flaky. If you create a while loop to read the file containing your hostnames and then send them as an argument to the Expect script, it will store it in the h variable.
That's what this line does:
Code:
set h [lindex $argv 0]
So to put it all together, let's say the Expect script is named sendCmd:
Code:
while read hosts;do sendCmd $hosts;done < my_server_list
or
while read hosts
do
sendCmd $hosts
done < my_server_list
I haven't found file I/O to be flaky in expect, but I must admit I only really use expect to test solutions posted in the forum. I find it a bit of a hacking tool and would prefer to use passwordless ssh for my own work.
The below script should open the server_list file, connect to each server run the configured command ("multibos -S" in this case) and log the output to a file name config_details with a "hostname:" prefix.
Also note: I'm using telnet in this script and you may want ssh or some other command.
Uncomment the log_user 0 line to suppress output once you have finished debugging.
Code:
#!/usr/bin/expect -f
set timeout 2
set u "souvikm"
set p "passw0rd"
set command "multibos -S"
set hosts [open server_list r]
set config [open config_details w]
#log_user 0
while {[gets $hosts host] >= 0} {
spawn -noecho telnet $host
expect "*User_ID*"
send -- "$u\r"
expect "?assword*"
send -- "$p\r"
send "PS1='PROMPT# '\r"
expect -re "PROMPT# '(.*)PROMPT# "
send "$command\r"
expect -re "\r\n(.*)\r\n(.*)PROMPT# "
set output $expect_out(1,string)
puts $config "$host: $output\r"
send "exit\r"
expect eof
}
close $hosts
close $config
Last edited by Chubler_XL; 02-25-2017 at 02:26 PM..
Tried tweaking in2nix's code to allign to my reqd with the following 'expect' code:
Code:
#!/usr/bin/expect -f
#
#
# set credentials
set u "msouvik"
set p "pass^123"
# get host name from command-line
set h [lindex $argv 0]
# set the command to run
set cmd "echo Hello Souvik! >> /export/home/msouvik/echo.out.$h"
# spawn a connection to the host and run the given command
spawn -noecho ssh -t $u@$h $cmd
# handle the password prompt
expect "?assword:*"
send -- "$p\r"
send -- "\r"
# scp the data onto NIM server
spawn -noecho scp $u@$h:/export/home/msouvik/echo.out .
# done
expect eof
And then applied the below 'while' loop:
Code:
while read h
> do
> expect_script.sh $h
> done < lsnim
Below is the error I get while the script tries to create a /export/home/msouvik/echo.out.$h file on the target servers:
==[ Error ]==
msouvik@my_target_server1 password: msouvik@my_target_server1 password:
scp: /export/home/msouvik/echo.out.my_target_server1: No such file or directory
msouvik@my_target_server2 password: msouvik@my_target_server2 password:
scp: /export/home/msouvik/echo.out.my_target_server2: No such file or directory ==
Find it really weird 'coz the script is not able to create a file named /export/home/msouvik/echo.out.$h on the target servers, however it is able to do so without the $h suffix to the filename.
Any leads pls?
-- Souvik P.S: I'll try to understand XL's script before I implement it tomorrow
I expected a response from one of you today, but none
I could manage to get my requirement by adding echo.out.$h in the scp portion of the script & not in the set cmd section as below:
Code:
cat expect_script.sh
#!/usr/bin/expect -f
#
#
# set credentials
set u "msouvik"
set p "pass^123"
# get host name from command-line
set h [lindex $argv 0]
# set the command to run
set cmd "echo Hello Buddy! >> /export/home/msouvik/echo.out"
# spawn a connection to the host and run the given command
spawn -noecho ssh -t $u@$h $cmd
# handle the password prompt for ssh
expect "Password:*"
send -- "$p\r"
send -- "\r"
# scp the data onto NIM server
spawn -noecho scp $u@$h:/export/home/msouvik/echo.out /export/home/msouvik/echo.out.$h
# handle the password prompt for scp
expect "Password:*"
send -- "$p\r"
send -- "\r"
# done
expect eof
However, this modification is creating a new problem - now the portion of code(highlighted in red) isn't working, it simply doesn't write to the file on the destination server. I've pasted the above code as it is from the server.
I'm not able to catch what happened to the working code with this small modification, could one you guys help me here? Excuse me (if) I'm forcing you guys to help
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