I have a HackRF, and I'm trying to figure out the best way to decode an On-Off Key digital signal. I'd like to just run a script (specifying the frequency and sample rate) and have it print out the digital signal in binary and/or hex. Does anything like this exist?
Sorry, I have not fully done this so my answer is not coming from experience. (I.e., I do not know offhand the best way to do this or have a personal favorite method or anything.)
However you might find some good info in https://greatscottgadgets.com/sdr/8/ ("Software Defined Radio with HackRF, Lesson 8: On-Off Keying") or by searching the web for "gnuradio ook" or "gnuradio ask".
Of course, you don't necessarily need to use GnuRadio, e.g. https://github.com/merbanan/rtl_433 and https://github.com/jimstudt/ook-decoder do OOK/ASK decode for many 433MHz/etc. devices albeit via RTL dongles rather than HackRF.
In some cases, often during preliminary stages reverse engineering where the exact encoding mechanism e.g. Manchester or whatnot is not yet known, I've seen some folks even decode the AM-recorded audio manually by carefully inspecting "the bumps" in Audacity. This is mentioned e.g. in some of the posts listed in http://www.rtl-sdr.com/tag/ook/ or in this thread or this blog post both about doing ASK decodes of a temperature sensor.