Expect – A tool for automating interactive applications

Wow, a blast from the past. I still have some expect tools I wrote long ago that I use and maintain to this day. Not so much new stuff since scripting languages have gotten better at doing what expect does -- often calling their modules "expect" and using the exact same syntax.

I once wrote a webserver in Expect. No, it's not a good language for writing a webserver.

Be sure to check out "autoexpect": it starts an interactive session, and generates an expect script based on that. Then you typically need to edit it for generalization (e.g., skip dates and time strings; often skip version strings, etc.).

I use it to install MySQL with some non default values. I'm not that good with bash and install scripts and expect was the only way around some issues I was having.

  secure_mysql_script=$(expect -c '
  spawn sudo mysql_secure_installation
  expect "Enter current password for root (enter for none):"
  send "\r"
  expect "Change the root password?"
  send "n\r"
  expect "Remove anonymous users?"
  send "y\r"
  expect "Disallow root login remotely?"
  send "y\r"
  expect "Remove test database and access to it?"
  send "y\r"
  expect "Reload privilege tables now?"
  send "y\r"
  expect eof
  ')
  echo "$secure_mysql_script"

For python, there's pexpect: http://pexpect.readthedocs.org/en/latest/

I used to use expect to automate a bunch of business reports and system functions. I switched to a python work-alike called pexpect that I still use and love. It feels a little hacky but it works and saves a huge amount of time over the course of a year.

I have been using a Ruby expect-like called Greenletters by Avdi Grimm, introduced on his blog here: http://devblog.avdi.org/2010/07/19/greenletters-painless-aut...

It's available via rubygems or github: https://github.com/avdi/greenletters

Oh expect. I've got a crappy little script I wrote when I was a sysadmin at Ticketmaster used to change a lot of our out of band management card passwords:

http://www.digitalprognosis.com/opensource/scripts/change_pa...

It might be useful to someone else.

Latest changes: May 1st, 2014 according to the changelog:

http://expect.cvs.sourceforge.net/viewvc/expect/expect/Chang...

Also, you can apt-get install `expect`.

I first discovered this about two months ago. It may be old, but it solved a problem we had and nothing else quite fit the job. We're using it to run a flaky test suite and count how many times it succeeds, fails, or times out (yes, times out - yay Android!). Very important when you're trying to determine if potential stability improvements actually make a difference or not, and you need to run the 3 minute suite ten times at least to get something statistically significant.

Has anyone used Expect for Windows? Any good experiences to share?

I'm wondering if it's something I should take the time to learn and use.

Here's a neat integration test suite written in expect for an HPC job launcher. Diving into this was my introduction to expect. It's a very practical little tool.

https://github.com/SchedMD/slurm/tree/master/testsuite/expec...

expect is one of the most useful system administration tools out there! I've used it to batch-modify settings on 100 machines where I couldn't just scp in a new file due to each one needing small variations.

If you don't know expect (and you're a sysadmin), learn it.

Oh, this is great old tool! :) Here's PHP extension for Expect that I've created back in 2005: http://pecl.php.net/package/expect

I love expect. We use it in upstart scripts. Little known gem of the unix world.

Expect is one of the few reliable ways I've found to automate crufty, closed source things. Say, like a perforce client pull that uses a caching proxy so that the proxy is up to date for actual human pulls.

We used Expect recently to automate iOS runtime hacking (ssh to jailbroken iOS device, run cycript to inject code, profit). One of those old Unix tools (built on tcl) that's very handy for automation.

It's very frustrating to see something like this that claims to be very useful, but shows no examples on the page.

>Expect is a tool for automating interactive applications such as telnet, ftp, passwd, fsck, rlogin, tip, etc. Expect really makes this stuff trivial.

How?

>Expect can make easy all sorts of tasks that are prohibitively difficult with anything else. You will find that Expect is an absolutely invaluable tool - using it, you will be able to automate tasks that you've never even thought of before - and you'll be able to do this automation quickly and easily.

HOW?

Ah, examples... >http://expect.sourceforge.net/#examples

It's just a giant README. This is frustrating.

It's wonderful for rapidly SSHing into a bunch of machines for doing automated things.

It's a fast hacking provisioning tool, I really like it for this purpose.

I remember seeing an elisp equivalent used to write ftp clients in emacs. Can't find it again, but anyway, I never got to see the original expect.

I once wrote a very minimal IRC client by essentially wrapping telnet around expect. All it did was automate sending out PINGs, but it worked.

Here is an alternative I use. http://empty.sourceforge.net/

I found the disclaimer interesting.

I remember this from writing chat(8) scripts. Pretty nice little language!

Love Expect, simple yet so functional.

Expect is great, however if you ever determine that using it is the best way to solve your problem, then you are probably approaching the problem the wrong way in the first place (the best way to proceed from that point may very well be to continue using expect though).

I used it a few years ago to create a test suite for some dedicated VoIP hardware (controlling the boxes over telnet). It worked great, but if I had had more time, that definitely would not have been my approach.