Expect – A tool for automating interactive applications(expect.sourceforge.net)

104 pointsby networked12 anni fa50 comments

expect.sourceforge.net

Expect – A tool for automating interactive applications

http://expect.sourceforge.net/

51 comments

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.

davidw12 anni fa

Tcl is a perfectly fine language for writing web servers with, actually. It was possible to do a nice, lightweight, evented web server years before Node.js showed up. AOLserver is also done with Tcl, and for a while in the 90ies, was one of the best systems for doing dynamic web sites.

ZoFreX12 anni fa

AOLServer is mostly C, is it not?

When you say it was one of the best systems for doing dynamic websites, would you use it on its own, or was it more popular to use OpenACS on top of it? (Which is what one of the codebases I still work on today does)

bch12 anni fa

IIRC, AOLServer is also the inventor of database connection pooling.

mcguire12 anni fa

My understanding was that AOLserver was the NCSA (pre-Apache httpd) server, with TCL as an extension language, not that AOLserver was written in TCL. Weird.

tptacek12 anni fa

Pairing with C is the whole point of Tcl; in its heyday, Tcl was known for having one of the easiest extension APIs of all the scripting languages. The idea of using a scripting language to knit C code together was one of Ousterhout's key goals.

Also: no other scripting language with the possible exception of JS has evented I/O so fundamentally baked into the core of the language.

davidw12 anni fa

Yes, it's a mixture of the two, which makes eminent sense if you consider the speed of computers 20 years ago.

It's Tcl, by the way, not TCL.

mcguire12 anni fa

Hey, if it was "Tool Command Language" when I first learned it, it's "TCL" now. :-)

Then there was that weird period when all the other language's gui toolkits were based on Tk.

VBprogrammer12 anni fa

Having spent time working on a million line Tcl codebase (for my sins) I can assure you that it is possible, but not in the least bit pleasant!

davidw12 anni fa

That I can see. But I can also see a lot of today's hip things, like Node.js, not being terribly fun either at that kind of size.

peterwwillis12 anni fa

Tcl shows up in all sorts of places, like Cisco IOS, or haptic feedback robotic surgery interfaces, or IRC bots. It's fast, it's small, it's robust, it's powerful. It's just not sexy.

thyrsus12 anni fa

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.).

zackmorris12 anni fa

How did I not know about this? Autoexpect is one of the thousand ways of interacting with computers that we USED to do back in the 80s and 90s that have since fallen out of favor. Macros, modem dialers, folder watchers, etc.. Remember trying the record button in Applecript Editor, only to find that it didn't actually work like it did in Macro Maker? The fact that autoexpect isn't installed by default on Mac OS blows my mind.

Edit: still trying to install autoexpect on Mac OS 10.9.2 and having no luck. Tried ActiveTcl at http://www.activestate.com/activetcl/downloads but it doesn't seem to have autoexpect. Tried brew install autoexpect, tried port install autoexpect, nothing. Sometimes unix reminds me of looking up hints in video game magazines upon finding oneself stuck, so if someone knows how to get autoexpect on Mac, please let us know because I'm throwing in the towel.

networked12 anni fa

Autoexpect comes bundled with Expect (it is an Expect script itself). Try

  brew install expect

[deleted]12 anni fa

iaskwhy12 anni fa

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"

pielud12 anni fa

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

klibertp12 anni fa

Something similar for Lua: http://www.tset.de/lpty/

chuto12 anni fa

We used to use tcl expect before discovering pexpect. Cleaner syntax, fewer false positives, nothing but good experiences with pexpect.

zwischenzug12 anni fa

I used pexpect as a base technology for ShutIt:

http://ianmiell.github.io/shutit/

it really is 95% of tcl's expect functionality, much easier to debug and understand. I'm grateful it exists, and it's much under-used I think.

emmelaich12 anni fa

Nice.

I have a somewhat similar tool but it doesn't do much besides check for password expiry and do password changes.

It uses pexpect but also multiprocessing and multiprocessing.Queue. I built most of it before we started using Ansible at work, but it is still useful in those places where Ansible is clumsy.

zwischenzug12 anni fa

Interesting - where is Ansible clumsy?

emmelaich12 anni fa

(just noticed this)

I was just sort of echoing your

    annoyed by the obfuscation and indirection of ...

Ansible's prime raison d'être is not remote execution but configuration management.

rPawel12 anni fa

It was great to see ShutIt during the last Docker London!

zwischenzug12 anni fa

Thanks! A previous similar talk is the first link here: https://www.youtube.com/user/ianmiell

rPawel12 anni fa

Thanks. Good luck Shutit and 2048 scores! :)

hcal12 anni fa

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.

jpgvm12 anni fa

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

SEJeff12 anni fa

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.

daveloyall12 anni fa

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`.

ZoFreX12 anni fa

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.

philbarr12 anni fa

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.

jasomill12 anni fa

Expect for Windows has been finicky for me every time I've tried using it, but Cygwin Expect works well, both for interacting with other Cygwin processes (not arbitrary Win32 console apps!), and for interacting with remote machines via (Cygwin) Telnet and SSH.

fintler12 anni fa

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...

nnnnni12 anni fa

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.

spektom12 anni fa

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

waterside8112 anni fa

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

npsimons12 anni fa

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.

jlturner12 anni fa

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.

throwaway_342412 anni fa

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.

nfriedly12 anni fa

Here's an example: https://github.com/nfriedly/Meteor-ODB-II/blob/master/deploy...

This script runs the meteor deploy command as part of my CI loop every time new code gets pushed to github. The deploy command expects me to type in a bunch of information, and expect does that for me.

klibertp12 anni fa

There are nice examples on wikipedia: http://en.wikipedia.org/wiki/Expect.

ff_12 anni fa

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.

agumonkey12 anni fa

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.

younata12 anni fa

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.

seqizz12 anni fa

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

cordite12 anni fa

I found the disclaimer interesting.

rikkus12 anni fa

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

lowlevel12 anni fa

Yeah, me too. I don't think I've needed anything like this since... I don't understand why it's news all of a sudden.

sseal12 anni fa

Love Expect, simple yet so functional.

Crito12 anni fa

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.