Conditional statament inside expect command called from a bash script

问题

I've been trying to automate some configuration backups on my cisco devices, i've already managed to do the script that accomplishes the task but I'm trying to improve it to handle errors too.

I think that's necessary to catch the errors on two steps, first just after the 'send \"$pass\r\"' to get login errors (access denied messages) and at the 'expect \": end\"' line, to be sure that the commands issued were able to pull the configuration from the device.

I've seen some ways to do it if you work on a expect script, but i want to use a bash script to be able to supply a list of devices from a .txt file.

#!/bin/bash

data=$(date +%d-%m-%Y)
dataOntem=$(date +%d-%m-%Y -d "-1 day")
hora=$(date +%d-%m-%Y-%H:%M:%S)
log=/firewall/log/bkpCisco.$data.log
user=MYUSER
pass=MYPASS

for firewall in `cat /firewall/script/firewall.cisco`
do

VAR=$(expect -c "
spawn ssh $user@$firewall
expect \"assword:\"
send \"$pass\r\"
expect \">\"
send \"ena\r\"
expect \"assword:\"
send \"$pass\r\"
expect \"#\"
send \"conf t\r\"
expect \"conf\"
send \"no pager\r\"
send \"sh run\r\"
log_file -noappend /firewall/backup/$firewall.$data.cfg.tmp
expect \": end\"
log_file
send \"pager 24\r\"
send \"exit\r\"
send \"exit\r\"
")

echo "$VAR"
done

回答1:

You need alternative patterns in the expect statements where you want to catch errors. If you're looking for a specific error message you can specify that, alternatively just specify a timeout handler which will eventually trigger when the normal output fails to appear.

Eg. after send \"$pass\r\" instead of expect \">\" try:

expect \">\" {} timeout {puts stderr {Could not log in}; exit}

ie. if the expected output arrives before the timeout (default 10 sec) do nothing and continue, otherwise complain and exit from expect. You might also need an eof pattern to match the case where your ssh session ends. Note that since you don't do any variable substitution in expect, you don't need \"\" around your strings, you can use {} or even nothing when it's one word, eg. expect conf and send {no pager}.

BTW I agree with bstpierre that this would be cleaner if you dropped bash and did the whole thing in expect, but if bash does the job that's ok.

回答2:

If you don't use single quotes (expect -c '...'), then all the $variables will be substituted by bash not expect. May be easier to put the expect code in a separate file, or maybe a heredoc.

来源：https://stackoverflow.com/questions/1638369/conditional-statament-inside-expect-command-called-from-a-bash-script