Combine uClinux and Asterisk on a Card

Expect and Embedded Systems

Expect is an extension to Tcl that lets you automate console sessions. I have found it to be very valuable for automating common steps in embedded systems work.

There are a couple of annoying problems with embedded system development:

Expect lets you automate all this. For example, here is some Expect code to transfer a file via FTP to the target system:

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

set tarball [lindex $argv 0]
set target  [lindex $argv 1]

send "ftp $target\r"
expect "): "
send "root\r"
expect "Password:"
send "uClinux\r"
expect "ftp> "
send "cd /var/tmp\r"
expect "ftp> "
send "put $tarball\r"
expect "ftp> "
send "quit\r"

It's as easy to write as it looks. In only a few minutes, you can automate common tasks. To run the script, simply type:

$ ./download tarball.tar.gz target

where target is the hostname of the target system.

You even can use it to set up configuration files for you (Asterisk has a million of these):

spawn telnet $target
send "cd /var/tmp/ipkg/asterisk\r"
expect "> "
send "cp -a etc/* /etc\r"
expect "> "
send "exit\r"

This example starts a Telnet session on the target and copies a bunch of files to /etc.

Expect can save you a lot of time in embedded systems work, closing the distance between embedded and regular desktop development.

Resources

Free Telephony Project: www.rowetel.com/ucasterisk/index.html

Blackfin uClinux Site: blackfin.uclinux.org

Building an Embedded Asterisk PBX, Part 1: www.rowetel.com/blog/?p=15

Building an Embedded Asterisk PBX, Part 2: www.rowetel.com/blog/?p=16

Optimizing code for the Blackfin: www.rowetel.com/blog/?p=5

gEDA Open EDA Tools: www.geda.seul.org