How do you save and parse a command output in Expect?

Question

Hi,

I am half-way through writing an Expect script on a Linux server which is supposed to telnet to a router in order to collect some system information. So far my script can successfully make the connection, run a router command, disconnect and terminate.

The command displays a few lines which I need to parse, something I am not sure how to do in Expect. How can I save the output, grep a line, then a column from the line, and finally save the result in a file? If possible, I would like to use Expect entirely rather than a work-around (for example Expect embdded in Bash).

Thanks for your time. jk04

Answer 1

basically, $expect_out(buffer) [1]. holds the output from last expect match to the current one. you can find your command output there.

and for the string manipulation, you can simply employ the tcl's built-in [2][3].

1. "How to access the result of a remote command in Expect" http://wiki.tcl.tk/2958
2. "regexp" http://wiki.tcl.tk/986
3. "string match" http://wiki.tcl.tk/4385

Answer 2

Two tips for expect development:

• autoexpect to lay out a framework for your automation
• exp_internal 1 to show verbosely what expect is doing internally. This one is indispensable when you can't figure out why your regular expression isn't capturing what you expect.