another EXPECT problem

Posted on 2001-09-10
Last Modified: 2012-06-27
Dear Solutions,

I have now one problem with expect where I am trying to generate one script to automate file transfer. The script will be run from machine A which will then telnet to machine B and create another Expect script on machine B which will then spawn another process into machine C and do the file transfer.

Since there could be more than 1 file to be transfer, i wanted to have a loop where, if there
is still file on then, continue transfering.

This is how the script looks like:

#!/usr/local/bin/expect -f

spawn telnet fieldu6
expect "login:"
send "spett\r"
expect "Password:"
send "spett\r"

expect "spett@fieldu6:"
send "cat>next-hop<<EOF\r"
expect "?"
send "#!/usr/local/bin/expect -f\r"
expect "?"
send "spawn ftp eqm31s14p2\r"
expect "?"
send "set transfer_flag 1 \r"
expect "?"
send "expect \"Name (eqm31s14p2:spett):\"\r"
expect "?"
send "send \"root\\r\"\r"
expect "?"
send "expect \"Password:\"\r"
expect "?"
send "send \"wpp_admin\\r\"\r"
expect "?"
send "expect \"ftp>\"\r"
expect "?"
send "send \"bin\\r\"\r"
expect "?"
send "send \"cd /Core/log/\\r\"\r"
expect "?"
send "expect \"ftp>\"\r"
expect "?"
send "send \"mget *.Z\\r\"\r"
expect "?"
send "send \"mget *.Z\\r\"\r"
expect "?"
send "expect \"*Z?\"\r"
expect "?"
send "send \"y\\r\"\r"
expect "?"
send "while {\$transfer_flag} { \\\r" #problem.
expect "?"
send "if {expect \"*Z?\"} { \\\r"
expect "?"
send "send \"y\\r\" \\\r"
expect "?"
send "} else { \\\r"
expect "?"
send "set transfer_flag 0 \\\r"
expect "?"
send "} \r"
expect "?"
send "interact\r"
expect "?"
send "EOF\r"
expect "spett@fieldu6:"
send "chmod +x next-hop\r"
expect "spett@fieldu6:"
send "./next-hop\r"

>>end of script
....continue here
? expect "ftp>"
? send "mget *.Z\r"
? expect "*Z?"
? send "y\r"
? while {$transfer_flag} { \  #problem here
transfer_flag: Undefined variable.
spett@fieldu6: /home/spett                       42 > if {expect "*Z?"} { \
? send "y\r" \
? } else { \
? set transfer_flag 0 \
? }
Missing }.
spett@fieldu6: /home/spett                        43 > interact

When i try to run this code, i have this error message, which to me seems that I didnt really escape the '$'sign which i think i already did.
How to solve this problem.

thanks alot.
Question by:mafendee
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Accepted Solution

kyrmit earned 100 total points
ID: 6532857
Your main problem is that the cat<<EOF>next-hop is a shell command and thus subject to the usual shell escapes. So not only does expect interpolate the $, but also the shell.

You can avoid a lot of hassle caused by the interpolation of expect here by using {} :
send {cat<<EOF>next-hop
while { \$transfer_flag } {

this allows the secondary script to be passwd without any interpolation, i.e. $ stay $ and " stay ", particularely the \$ stays \$ for the shell.

However, you may find the ftp command 'prompt' useful which
toggles the question during mget from on to off. See the ftp man page for it's usage. By issuing "bin" and "prompt" the ftp client will never ask you if you really want to get a file during mget. This bypasses the need for the while loop in this case altogether.

One more thing: there is an error in the loop in that expect is used as the parameter to an if. This won't work, try something the like. I am using a catchall fallback by
using the regular expression .*.

while { $transfer_flag } {
        expect -re ".*\? " {
                send "y\r"
        } -re ".*" {
                set transfer_flag 0

Hope this helps

Author Comment

ID: 6630724
its works! thanx

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