Use of expect to run scripts on remote machine - linux

I am working on a project that requires some assistance.
I have automated most of the information required for the completion of this project but the only thing that is lagging is the running of local shell scripts on the remote machine.
As we are aware that no Linux command is recognized by the script that uses the 'expect' library.
Herein we have two use cases that I have tried:
1) Running the desired list of commands on the remote server using only one expect script which has both the script execution as well as pushing of output using scp to the local machine, here is a snippet of this code:
`chmod 777 localscript.sh
cat > script1.sh <<- "ALL"`
`#!/usr/bin/expect
set password [lindex $argv 0];
set ipaddress [lindex $argv 1];
set timevalue [lindex $argv 2];
set timeout $timevalue
spawn /usr/bin/ssh username#$ipaddress /bin/bash < ./localscript.sh
expect "assword:"
send "$password\r"
set timeout $timevalue
spawn /usr/bin/scp username#$2:"/path/from/source/*" /path/to/destination/folder/
expect "assword:"
send "$password\r"
interact
ALL
chmod 777 script1.sh
./script1.sh $password $2 $timevalue`
2) Running the desired list of commands on the remote server in a separate expect script and using scp to get files in a different script:
`cat > script1.sh <<- "ALL" `
`#!/usr/bin/expect
set password [lindex $argv 0];
set ipaddress [lindex $argv 1];
set timevalue [lindex $argv 2];
set timeout $timevalue
spawn /usr/bin/ssh username#$ipaddress /bin/bash < ./localscript.sh
expect "assword:"
send "$password\r"
interact
ALL
cat > script2.sh <<- "ALL2"`
`#!/usr/bin/expect
set password [lindex $argv 0];
set ipaddress [lindex $argv 1];
set timevalue [lindex $argv 2];
set timeout $timevalue
spawn /usr/bin/scp username#ipaddress:"/path/from/source/*" /path/to/destination/folder/
expect "assword:"
send "$password\r"
interact
ALL2
chmod 777 localscript.sh script1.sh script2.sh
./script1.sh $password $2 $timevalue
sleep 5
./script2.sh $password $2 $timevalue`
I believe the above codes should both be valid in their own respect however, the output for the same seem to be quite unexpected:
1) Both the commands ssh and scp are being executed almost simultaneously after password is entered hence, it is not giving localscript enough time to do its job, here's the output I see:
spawn /usr/bin/ssh username#1.2.3.4 /bin/bash < ./localscript.sh
Warning private system unauthorized users will be prosecuted.
username#1.2.3.4's password: spawn /usr/bin/scp
username#1.2.3.4:"/home/some/file/*" /another/file/
Warning private system unauthorized users will be prosecuted.
username#1.2.3.4's password:
scp: /home/some/file/*: No such file or directory
Please note: This functionality is working fine without the involvement of expect
2) Here we are executing ssh and scp separately, however, it seems like it is unable to recognize that the file localscript.sh exists:
spawn /usr/bin/ssh username#1.2.3.4 /bin/bash < ./localscript.sh
Warning private system unauthorized users will be prosecuted.
username#1.2.3.4's password:
bash: localscript.sh: No such file or directory
Warning private system unauthorized users will be prosecuted.
username#1.2.3.4's password:
scp: /home/some/file/*: No such file or directory
Any feedback on the same would be appreciated, I think the first approach might be a feasible solution, except the fact that spawn is too fast and none of the 'sleep' or 'after' commands are helping/working. I think the second approach is also valid however it seems like there is a different way of running a local script on a remote server than the usual way we do on Linux when using 'expect'.
Sorry for so much elaboration, I am hoping to be out of my misery soon :)

Indeed the timeout you are setting is not working as you expect it to. Both scripts are spawned, and the expect "assword:" after each spawn is actually catching and reacting to the same password prompt.
expect is actually more sophisticated than a cursory glance would lead you to believe. Each spawn should return a PID, which you can use with your expect to look for output from a specific process.
expect can also be broken down into multiple parts, and have the ability to define subroutines. Here are some more advanced use examples https://wiki.tcl-lang.org/10045
In this specific case I would suggest waiting for the scp to complete before spawning the next process.
expect {
"assword:" {
send "$password\r"
exp_continue # Keep expecting
}
eof {
puts -nonewline "$expect_out(buffer)"
# eof so the process should be done
# It is safe to execute the next spawn
# without exp_continue this expect will
# break and continue to the next line
}
}

Related

expect command is not passing env variable in ubuntu focal

I'm using expect (v5.45.4-2build1) to automate generation of client certs using easy-rsa in ubuntu focal.
As per easy-rsa, to customize cert validity we need to pass EASYRSA_CERT_EXPIRE variable.
But for some reason, my expect script is not able to fetch this variable.
Here's the code for script.exp:
#!/usr/bin/expect -f
set timeout -1
#exp_internal 1
set MY_PASSPHRASE [lindex $argv 0];
set USERNAME [lindex $argv 1];
set ttl [lindex $argv 2];
send "export EASYRSA_CERT_EXPIRE=$ttl\r"
spawn /bin/bash
set MSG "Executing script.exp for $USERNAME and $ttl";
send "echo 'INFO $MSG'>> /var/log/app/my_app.log\r"
send "cd /etc/openvpn/easy-rsa\r"
send "export EASYRSA_CERT_EXPIRE=$ttl\r"
send "./easyrsa gen-req $USERNAME\r"
expect "*Enter PEM pass phrase:"
send -- "$MY_PASSPHRASE\r"
expect "*Verifying - Enter PEM pass phrase:"
send -- "$MY_PASSPHRASE\r"
expect "*Common Name *$USERNAME*"
send -- "\r"
expect "*Keypair and certificate request completed*"
send -- "\r"
exit 0
Strangely, this works fine if i run the script via expect script.exp.
But I want to use this in my perl script and it is not working from the perl script.
This is how I'm calling my expect script:
my $cmd_out_csr = system("expect script.exp $my_passphrase $username $ttl");
Just running, expect script.exp $my_passphrase $username $ttl from cmd works fine.
Any help is appreciated.
Thanks.
use the perl system command with a list of arguments:
system('expect', 'script.exp', $my_passphrase, $username, $ttl);
when creating the variable in the remote shell, send quotes around the value:
send "export EASYRSA_CERT_EXPIRE=\"$ttl\"\r"
These two things will protect the value of $ttl if it contains whitespace.
Another thought: expect (via Tcl) can cd and set environment variables. Instead of spawning a bash shell, spawn easyrsa directly:
#!/usr/bin/expect -f
set timeout -1
#exp_internal 1
lassign $argv MY_PASSPHRASE USERNAME ttl
set f [open /var/log/app/my_app.log a]
puts $f "INFO Executing [info script] for $USERNAME and $ttl"
close $f
cd /etc/openvpn/easy-rsa
set env(EASYRSA_CERT_EXPIRE) $ttl
spawn ./easyrsa gen-req $USERNAME
expect "*Enter PEM pass phrase:"
send -- "$MY_PASSPHRASE\r"
expect "*Verifying - Enter PEM pass phrase:"
send -- "$MY_PASSPHRASE\r"
expect "*Common Name *$USERNAME*"
send -- "\r"
expect "*Keypair and certificate request completed*"
send -- "\r"
expect eof
puts "Done."

What's the best way to mix remote expect scripts and local bash commands?

I'm automating tasks on a local and remote machine (behind a firewall). Once I'm done with tasks on the remote machine, I'd like the script to return to executing commands on the local machine.
#!/usr/bin/expect -f
set timeout -1
spawn ssh username#host
expect "Password: "
send "mypassword\r"
expect "username#host:~$"
...do some stuff...
send "exit\r"
expect eof
[then, once on the local machine, change directories and do other things]
What's the best way to append bash commands? I suppose I could start with bash, call expect within it, then simply return to bash once expect is done.
Expect is based on Tcl, so it can run the same commands. But if your goal is to run bash commands, the best bet is to run them from bash as a separate script, exactly as you propose in your last sentence.
It really depends on what your idea of ...do some stuff... is. Here's an example of something I recently did from my OSX w/s to an AWS instance
export all_status
init_scripts=($(ssh -q me#somehost 'ls /etc/init.d'))
for this_init in ${init_scripts[#]};do
all_status="${all_status}"$'\n\n'"${this_init}"$'\n'"$(ssh -q somehost \'sudo /etc/init.d/${this_init} status\')"
done
echo "$all_status" > ~/somehost_StatusReport.txt
unset all_status
Passing a command at the end of the ssh command will cause the command to be run on the remote host. Or you can scp a script to the remote host and run it with
ssh somehost '/home/me/myscript'
I met this situation recently too. I make a shell supexpect.sh which could login and execute command automatically. It will return to your local shell at the end.
#!/usr/bin/expect
#Usage:supexpect <host ip> <ssh username> <ssh password> <commands>
set timeout 60
spawn ssh [lindex $argv 1]#[lindex $argv 0] [lindex $argv 3]
expect "yes/no" {
send "yes\r"
expect "*?assword" { send "[lindex $argv 2]\r" }
} "*?assword" { send "[lindex $argv 2]\r" }
send "exit\r"
expect eof
To execute:
./supexpect.sh 10.89.114.132 username password "ls -a;pwd;your_stuff_on_remote_host"
Note:
The prompt might need to adapt to your own system, and of course you need to pass execute permission to it.

Running shell command after expect login

Iam trying to exceute a command after logging in to a linux RHEL box using expect and interact.
Below is script
#!/usr/bin/expect
set timeout 100
set temp [lindex $argv 0]
spawn ssh userid#10.20.30.40
expect "Password:"
send "password\n";
interact
expect "*3.2*"
send "./p.sh\n";
Its successfully logging in to the box but after that its not excecuting the command.
This is the actual output of the commnad after login , which iam trying to exceute.
Using keyboard-interactive authentication.
Password:
Last login: Sun Mar 22 11:04:01 2015 from com
-sh-3.2$ pbrun pbapp wasapp=ksh
Please note home directories are intended only for user/application profiles.
$
These are the errors i received
-sh-3.2$ exit
logout
Connection to 10.20.30.40 closed.
expect: spawn id exp7 not open
while executing
"expect "*$""
(file "./testWas.sh" line 8)
when i try
expect "*$"
exec "pwd"
-sh-3.2$ exit
logout
Connection to 10.20.30.40 closed.
couldn't execute " pwd ": no such file or directory
while executing
"exec { pwd }"
(file "./testWas.sh" line 8)
Edit:
Thanks to red #glenn jackman
iam able to excute pbrun commands after login..
But after excecuting the pbrun command script is exiting
#!/usr/bin/expect
set timeout 100
set host [lindex $argv 0]
set username [lindex $argv 1]
set password [lindex $argv 2]
set command [lindex $argv 3]
spawn ssh $username#$host expect "Password:"
send "$password\n";
expect -re {\$ $} ; # put here string from your server prompt
send "./p.sh\n";
expect -re {\$ $} ;
send "pwd\n";
This is the content of p.sh
Only first line of the script is executing..
-sh-3.2$ cat p.sh
pbrun pbapp wsapp=ksh
pwd
clear
-sh-3.2$
There is a similar unanswered question
How to run "pbrun pbapp wasapp=ksh" command using SSH java client?
interact tells expect that you are going into manual mode, where you, the human, is in control of the spawned command. I see you then typed exit which ended the ssh session. Since the spawned command ended, the interact command ended and control returned to the script. The next command dies because the spawned command is not running.
Simply put, remove interact:
#!/usr/bin/expect
set timeout 100
set temp [lindex $argv 0]
spawn ssh userid#10.20.30.40
expect "Password:"
send "password\r" # a carriage return more exactly represents
# "hitting enter"
expect -re {\$ $} # this regular expression matches the end of the prompt
send "./p.sh\r"
if { you want to interact manually with the ssh session } {
interact
} else {
expect -re {\$ $} # if p.sh exits the ssh session, remove this line
send "exit\r" # and this one too.
expect eof
}

How to pass a parameter form perl in linux expect script?

I have to pass a path at runtime as the abc.sh script will prompt for it .. I am trying following expect script to accomplish this,
#!/usr/bin/expect -f
set force_conservative 0
if {$force_conservative} {
set send_slow {1 .1}
proc send {ignore arg} {
sleep .1
exp_send -s -- $arg
}
}
spawn abc.sh
match_max 100000
expect -exact "Please enter path : "
send -- $path
expect -exact "\r
expect eof
Need your help – how I can pass $path values at run time calling like this ?
expect script.exp $path
Thanks,
Expect Answer
Use send -- $argv in your expect script because $argv holds the command line arguments.
As an example, I've this handy expect script that interacts with ssh commands when admins stupidly disable public key authentication :
#!/usr/bin/expect -f
set timeout -1
set send_human {.6 .1 1.6 .1}
eval spawn $argv
match_max 100000
expect {
-re "LOGIN#(\[0-9A-Za-z_\\-\\.\]+)'s password: "
{ sleep 0.6 ; send -- "PASSWORD" ; sleep 0.1 }
interact
Use constructs like [lrange $argv 0 $argc] if you need only part of the $argv
Perl Answer
Use system 'script.exp' $path to call script.exp from a perl script, assuming use chmod, etc., roughly like DeVadder said sans the quotes. Or use exec if your perl script wishes to terminate. Run man perlfunc to read about perl commands.

spawn_id: spawn id exp6 not open

I know that this issue is already mentioned here, but the solution does not work for me.
I have this script (let's name it myscript.sh) that spawns a process on remote environment and that should interact with it.
#!/usr/bin/expect
log_user 0
set timeout 10
spawn ssh -o PubkeyAuthentication=no [lindex $argv 0] -n [lindex $argv 1]
expect "password:" {send "mypassword\r"}
expect "Continue to run (y/n)" {send "n\r"}
interact
When I call this script on local environment...
myscript.sh user#host "command1;./command2 parameter1 parameter2"
I get the above error at line 7 (interact)
Any ideas??
I suspect the expect is not able to find out(matching) the pattern you are sending.
expect "password:" {send "mypassword\r"}
expect "Continue to run (y/n)" {send "n\r"}
Check out again whether the "password:" and "Continue to run (y/n)" are in correct CAPS.
If still getting the same error, you can try using regular expression.
Try to do a normal ssh without script. See if it works. Sometimes the remote host identification changes, and the host has a new ip or new key. Then it helps to remove the old key with ssh-keygen -f ~/.ssh/known_hosts -R old_host, or something similar.
I had this problem and it was down to using the wrong port.
/usr/bin/expect <<EOF
spawn ssh-copy-id -i $dest_user#$ip
expect {
"yes/no" {
send "yes\r";exp_continue
} "password" {
send "$passwd\r"
} eof {
exit
}
}
expect eof
EOF
I ran into this issue as well but it was due to me creating/editing the following file for an unrelated item:
~/.ssh/config
Once I deleted that, all my scripts began working and I no longer got that issue with my expect file.

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