I wrote my first Expect script without using functions, its task is to connect to a remote host via SSH, then from the remote host start a TFTP copy.
I want to offer the user the option to copy another file, then I thought I would need to change my Expect code from a single sequence of lines and split it into functions.
First function would be to spawn SSH:
proc Connect {sshOptions userName switchIP userPassword aclFile} {
spawn -noecho ssh "$sshOptions" $userName#$switchIP
log_user 0
expect {
timeout exit
-exact "Password:" { send -- "$userPassword\r" }
}
expect "*test#"
send_user "Connection established\n"
}
Second function would be to start the copy:
proc Copy_ACL {aclFile} {
send_user "Copying ACL file...\n"
send "***copy command here**"
expect "TFTP get operation was successful"
send_user "ACL File copied\n"
}
Then I call functions as follows:
Connect $ssh_Options $user_Name $switch_IP $user_Password $acl_File
Copy_ACL $acl_File
At the moment, the issue I am facing is that, it seems function "Copy_ACL" does not know anything about the SSH session spawned by the previous function Connect. The copy command is sent to stdout although "log_user" has been set to 0.
What am I missing?
Also, is there another book about Expect besides "Exploring Expect"?
I had some success modifying existing code to use the same Expect session in two procs. All that seemed to be necessary was to make expect_out and spawn_id global variables so they could be shared between the procs. Of course, this means that only one Expect session can run at once, but that isn't likely to be a problem.
Related
I'm working on a small project for school. I'm using 15 or so tuners to emulate a Cell network. I'm by no means well versed in scripting yet. I'm an EE who usually googles until I have some frankencode capable of my purposes.
The goal is the set up all the modules quickly so I thought to automate the process with a script. This requires ssh, and so far I have to manually type in the password each time. This morning I set up a basic test with both Expect and sshpass. In either case I can correctly log in, but not give instructions to the remote machine.
I was reading that sshpass has difficulty with sending remote instruction, correct me if I'm wrong.
/usr/bin/expect << EOF
spawn ssh root#<IP>
expect "(yes/no)?" #Are you sure you want to connect nonsense
send "yes\r"
expect "password"
send "$pass\r"
I tried a few things here to get the device to receive instruction
interact
cat /pathto/config.txt
#or
send "cat /pathto/config.txt
#the real goal is to send this instruction
sqlite3 /database.db "update table set param=X"
EOF
You might as well make it an expect script, not a shell script
#!/usr/bin/expect -f
and then pass the IP address to the script as a command line argument
expect myloginscript.exp 128.0.0.1 the_password
In the expect script, you'll grab that IP address from the arguments list
set ip [lindex $argv 0]
set pass [lindex $argv 1]
(Putting the password on the command line is not good security practice. You can research better methods of passing the password to your expect script.)
To use ssh, you'll be asked "are you sure" only the first time to connect, so let's make that conditional. That is done by letting the expect command wait for several patterns:
spawn ssh root#$ip
expect {
"(yes/no)?" {
send "yes\r"
# continue to wait for the password prompt
exp_continue
}
"password" {
send "$pass\r"
}
}
Once that is sent, you should expect to see your shell prompt. The pattern for this is up to your own configuration but it typically ends with a hash and a space.
expect -re {# $}
Now you can automate the rest of the commands:
send "cat /pathto/config.txt\r"
expect -re {# $}
# note the quoting
send "sqlite3 /database.db \"update table set param='X'\"\r"
expect -re {# $}
At this point, you'll want to log off:
send "exit\r"
expect eof
On the other hand, if you set up ssh private key authentication (see ssh-keygen and ssh-copy-id), you can just do this:
ssh root#IP sqlite3 /database.db "update table set param='$X'"
and not have to get into expect at all.
Can anyone help me in creating an expect script to just do an SSH on a list of servers and check if it was fine. I do not need to interact, do not need to fire any command on each server, I just want to do an ssh and come out, with a return code mentioning whether it was successful or not.
Expect is important here, as I do not have an option to setup a passwordless connection. Also there is a possibility that passwordless connection is setup on some of those servers.
I tried something like:
#!/usr/local/bin/expect
set timeout 10
set ip [lindex $argv 0]
set user [lindex $argv 1]
set password [lindex $argv 2]
set prompt "(>|%|\\\\\\\$|#|]|) \$"
spawn ssh "$user\#$ip"
expect "Password:"
send "$password\r"
send "echo hello\r"
expect "hello"
send "exit\r"
But this gets stuck on the first server, and does nothing after that.
Thanks,
Piyush
A generalized idea can be having a procedure to spawn the ssh and close the connection which will maintain the connections local to the scope, so that global spawn_id won't get affected at all.
#!/usr/bin/expect
proc isHostAlive {host user pwd} {
# We escaped the `$` symbol with backslash to match literal '$'
# Commonly used prompt types
set prompt "#|%|>|\\\$"
set timeout 60
spawn ssh $user#$host
expect {
timeout {return FAIL}
"(yes/no)" {send "yes\r";exp_continue}
"password:" {send "$pwd\r";exp_continue}
-re $prompt
}
set msg "Hello World"
send "echo $msg\r"
expect {
timeout {return FAIL}
"\r\n$msg"
}
send "exit\r"
expect {
timeout {return FAIL}
eof
}
return PASS
}
# Lists to maintain the each host's information
set serverList {server1 server2 server3}
set userList {user1 user2 user3}
set pwdList {pwd1 pwd2 pwd3}
# Looping through all the servers and checking it's availability
foreach server $serverList user $userList pwd $pwdList {
puts "\n==>Status of $server : [isHostAlive $server $user $pwd]\n"
}
With exp_continue, we can handle even if any host does not have password. Basically exp_continue will cause the expect to run again. So, among the mentioned phrase whichever comes, it will be handled. i.e. if expect sees (yes/no), it will send yes, if expect sees password, it will send the password value and so on. Then expect will continue to wait for the whole set of phrases again.
The reason why I have added yes/no is because if suppose the host's RSA fingerprint needs to be saved.
After successful login, I am echoing Hello World and expecting for the echoed message. If you have noticed, I have used \r\n$msg in the expect statement. Why do we need \r\n here ?
Here is why. Whenever we send command that will be seen by the expect also and it will try to match against that too. If it matched, it will proceed as such.
Sample echo command output
dinesh#dinesh-VirtualBox:~/stackoverflow$ echo Hello World
Hello World
dinesh#dinesh-VirtualBox:~/stackoverflow$
The string we want to expect is already available in the send command. So, to make sure the matching expect string is only from the actual echoed response, I have added \r\n which will help us in matching what is necessary.
Then at last of the proc, I am sending exit command which will close the ssh connection and to match the same eof (End Of File) is used. In all sort of failure cases, the procedure will return FAIL.
I am trying to write a bash script that uses expect to scp a file to remote systems. The expect block that I have so far looks like this
expect -c "
set timeout -1
spawn scp $file user#host:$file
expect "\Are you sure you want to continue connection (yes/no)\"
send -- \"$password\r\"
expect eof
"
The problem is that this handles the case in which the host is not a known host and it asks if I want to continue connecting. I would like to add a an option for the case in which the host is already known and it simply wants the password.
The other issue is that I would like to handle the event in which the password the user entered is not correct. In that case, I would like to have the user reenter the password.
What would be the best way of accomplishing this using bash and expect?
Many thanks in advance!
host is not a known host and it asks if I want to continue connecting
Use: scp -o "StrictHostKeyChecking no" <...>
event in which the password the user entered is not correct
If your script is considered to be interactive, why you are using expect at all? scp can ask and re-ask a password by itself.
Like this:
expect -c "
set timeout -1
spawn scp $file user#host:$file
expect
{Are you sure you want to continue connection (yes/no)} {
send \"yes\r\"
exp_continue
}
{Password: } {
send -- \"$password\r\"
}
}
expect eof
"
The exp_continue command loops back to the containing expect command so that other patterns have a change to be matched.
I am new to Expect scripting.
I wrote an Expect script for ssh in a Linux machine, where I am facing a problem in ssh'ing to different Linux machines. Below I have copied the script.
!/usr/local/bin/expect
set LinuxMachine [lindex $argv 0]
spawn ssh root#$LinuxMachine
expect "root#$LinuxMachine's password:"
send "root123\n"
expect "[root#Client_FC12_172_85 ~]#"
send "ls"
interact
When I supply 10.213.172.85 from command line the expect in the 4th line, it reads as "root#10.213.172.85's password:" and logs in successfully
But some Linux will expect
The authenticity of host '10.213.172.108 (10.213.172.108)' can't be established.
RSA key fingerprint is da:d0:a0:e1:d8:7a:23:8b:c7:d8:40:8c:b2:b2:9b:95.
Are you sure you want to continue connecting (yes/no)
In this case the script will not work.
How can I have two Expect statements in one Expect command?
You can use exp_continue in such a case:
expect {
"Are you sure you want to continue connecting (yes/no)" {
send "yes\r"
exp_continue
}
"root#$LinuxMachine's password:" {
send "root123\r"
expect "[root#Client_FC12_172_85 ~]#"
send "ls\r"
interact
}
}
In the above, the Expect block waits for either the yes/no question OR the prompt for password. If the latter, it moves on with providing password, expecting prompt, sending ls command and giving control back.
If the former, it will answer 'yes' and repeat the expect block, ready to find the prompt for a password (or even the yes/no question again, for that matter - not that you will need that).
I would also include some timeouts with meaningful messages in case some expect option does not match as expected, but the above should work.
As a side comment, you don't want to set a root password in a script... I recommend using ssh key authentication.
We like to call it "long log in". There are ssh options that don't check the host keys:
send -- "ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no username#host\n"
expect {
"Password" {
send -- "$passwd\n"
}
Part of the Bash script that calls on the expect sets the password:
echo -n "Enter LDAP password: "
read -s passwd
echo
This is the first time I am writing a shell script. I tried to do as much research as I can to avoid dumb/repetitive question. Please excuse if its repeat/dumb question.
I have a shell script which connects to remote linux machine and runs scripts there. I am using 'expect' to spawn a ssh connection and to issue commands to trigger the job. However, I am having issues while closing the connection after completing the job.
This is my script:
set prompt "(%|#|\\$|%\]) $"
expect -c 'spawn ssh $UN#$STAGE ;
expect password ; send "$PASS \n";
expect -regexp "$PROMPT"; send "./settings.$UN.sh > settings_log.txt \n";
interact'
This script successfully runs the script file for me ($UN and $STAGE parameters are input to the script. I omitted that here for simplicity). However, this leaves me with an open connection.
I tried to close the connection after running the script by using following instead of above
expect -c 'spawn ssh $UN#$STAGE ;
expect password ; send "$PASS \n";
expect -regexp "$PROMPT"; send "./settings.$UN.sh > settings_log.txt \n";
expect -regexp "$PROMPT"; send "exit \n"'
This does close the connection but I noticed that my script file did not run at all. Also the settings_log.txt is not generated at all.
Does this mean, that exit command is aborting the process before its completion? I tried using 'sleep' before exit but it did not help. Is there a better suggested way to terminate the connection when using expect?
Any help is appreciated.
with expect, you terminate your send commands with \r not \n, so
expect -c 'spawn ssh $UN#$STAGE
expect password
send "$PASS\r"
expect -regexp "$PROMPT"
send "./settings.$UN.sh > settings_log.txt\r"
expect -regexp "$PROMPT"
send "exit\r"
expect eof'
Note you can execute remote shell commands and copy files using ssh and scp, directly, without using expect.
For example,
scp ./settings.$UN.sh $UN#$STAGE:settings_log.txt
ssh $UN#$STAGE whatever-you-need-to-execute
The connection will close as soon as soon as whatever-you-need-to-execute completes.
Your outer script seems to be written in csh and sets a variable named "prompt", but your expect script is using a variable called "PROMPT". Try making the two variable names match case.