Unable to run tcl script via crontab(buffer error)

pantelis1 · ‎10-31-2013

Hi All

I am correcrtly executing the script below from my linux server. However, it seems that once I try to run it via crontab (correct permisions have been set etc) I get the following error:

can't read "expect_out(buffer)": no such variable

while executing

"set output $expect_out(buffer)"

("foreach" body line 6)

invoked from within

"foreach cmd $commands {

send "$cmd\r"

expect -re $prompt

#remove zeros from the cmd filename

regsub -all {[ \r\t\n]+} ..."

("foreach" body line 20)

invoked from within

"foreach device $device_list {

# Set each device's log file to be the name of the device...

set file_name $device

# we initiate the SSH connection

Crontab is:

0 4 * * * /usr/bin/expect /<path of the script>/<script name>.exp

Script below:

#!/usr/bin/expect

# Here, we specify all our commands in a list, that we will issue one

# by one at a later time.

set commands [list "show ip route summary" "show interfaces" "show arp" "show ip ospf neighbor" "show ip eigrp neighbor" "show cdp neighbors"]

# Set the date.

set date [timestamp -format %C%y%m%d]

# This variable is for a file called switches.txt that has the hostname/IP

# of all of the routers you are collecting information from.tepad

set device_list [read [open "/<path>/switches.txt"]]

# Specify the username and password, as well as what we expect the routers'

# prompt to be.

set pass "*******"

#set prompt "#"

set prompt {([#>]) ?$}

# This command tells expect not to echo the output to the console.

exp_log_user 0

#log_user 1

# We loop through each device in our list, one by one...

foreach device $device_list {

# Set each device's log file to be the name of the device...

set file_name $device

# we initiate the SSH connection

eval spawn ssh $device -l ********

match_max [expr 32 * 1024]

#If we see a message asking about the device's host key, accept it.

interact -o -nobuffer -re "assword: $" return

send "$pass\r"

# Loop through each command that we specified earlier.

expect -re $prompt

send "term len 0\r"

expect -re $prompt

foreach cmd $commands {

send "$cmd\r"

expect -re $prompt

#remove zeros from the cmd filename

regsub -all {[ \r\t\n]+} $cmd "" correct_cmd

set output $expect_out(buffer)

set fd [open /<path>/$file_name-$date-$correct_cmd.txt w]

puts $fd $output

close $fd

}

expect -re $prompt

send "exit\r"

exp_close -i $spawn_id

exp_wait

}

Not sure why this is the case. Anyone can recommend a solution?

Thanks

Pantelis

Joe Clarke · ‎11-02-2013

Could it be that you need to fully-qualified path to ssh? I'd think it would fail earlier, though. You may want to re-enable user logging and exp_internal to see what expect is doing when run from within cron.

pantelis1 · ‎11-03-2013

hI Joseph

I have already done that and the problem is below:

can't read "expect_out(buffer)": no such variable as per my initial post

Thanks

Pantelis

Joe Clarke · ‎11-03-2013

But if you enable more debugging, you will see the what is being sent/received to/from the device. If this variable isn't being set, there is something with the match criteria. What is the full output when you have log_user and exp_internal enabled?

pantelis1 · ‎11-04-2013

Hi Joseph

Even after enabling log_user 1 I am still not able to get any errors (to be honest I am not getting the buffer error either this time ). The relevant config is :

I have also edited the crontab to output the file as per below:

Crontab is:

0 4 * * * /usr/bin/expect //

Joe Clarke · ‎11-04-2013

Can you try fully-qualifying the ssh path. For example:

spawn /usr/bin/ssh x.x.x.x -l ****

pantelis1 · ‎11-05-2013

It performs exactly the same but this time produces :

spawn /usr/bin/ssh x.x.x.x -l ****

Joe Clarke · ‎11-05-2013

Sorry then. I'm out of ideas. I'm not seeing the debug I'd expect. Maybe there's a problem with your cron implementation. Could also be an environment variable you need to set or not set...

Maher Abdelshkour · ‎12-18-2013

Hello Pantelis,

You need to declare the whole of expect_out global rather than just one element.

Thank you!

pantelis1 · ‎12-19-2013

Hi Maher

Could you please elaborate on this?

Thanks

Pantelis

Maher Abdelshkour · ‎12-19-2013

Pantelis,

Use the curly braces to avoid substitution.

1. interacting with a program on your local machine:

#!/usr/bin/expect -d

spawn "/bin/bash"

send "term len 0\r"

expect -re eof

puts $expect_out(buffer)

2. interacting with a remote program over ssh:

!/usr/bin/expect -d

spawn ssh user@hostname

set prompt ":|#|\\\$"

interact -o -nobuffer -re $prompt return

send "mypassword\r"

interact -o -nobuffer -re $prompt return

send $cmd

send "exit\r"

expect eof

puts $expect_out(buffer)

Hope this helps

Regards!