Shell Programming and Scripting

No worries... just so you know, there are those among us who periodically search for "unanswered questions", so if you just wait, someone who knows the answer should pick it up eventually. By bumping the post with a reply you prevent it from being found by such a query.

Your original code seems to work fine more-or-less if you just remove the redirection to file descriptor 4 (by doing this you are taking it away from &p) and then use read -p to read the output into a variable, perhaps in a while loop. You can use some logic in the while loop to recognise the line of output you're expecting.

The only problem is... if for some reason it fails to log in, or you don't find the output you're expecting, the while read -p variable loop will block waiting for more input from the pipe, so you'd need some kind of timeout facility (another background process?) to prevent your script running forever.

Try this:

Code:

telnet $HOSTNAME |&
sleep $DELAY
print -p $UNAME
sleep $DELAY
print -p $PWORD
sleep $DELAY
print -p uptime
sleep $DELAY
while read -p UPTIME
do
        print "read line:$UPTIME" | cat -vet
        if [[ "$UPTIME" = *average:* ]]
        then
                print found the uptime
                break
        fi
done
print -p exit
print the uptime is $UPTIME

The trouble with that approach is that the remote host could have a login banner. Our hosts do and it's about 15 lines of lawyer language. But every now and then we encounter a host without the approved message or with an older version of the message. Then there could be a /etc/motd. Everybody had to give me an account on any company box so that I could verify security issues. But I wound up with 6 different prompts. Stuff like this is what you encounter when you are automating access to hundreds of systems. The flying blind approach works in the face of these issues.

Yep, I know exactly what you mean... although that shouldn't hinder my solution above unless the uptime output doesn't contain "average:". I had the same problem as you with a large number of systems and expect, just trying to find regex that matched the various "password:", "Password:", "password: ", etc. and shell prompts was a challenge. Sometimes it's simpler to just issue a PS1=expectshellprompt: or similar as the first command!