GNU poke 1.0 | Hacker News Reader

GNU poke 1.0

jemarch.net

196 pointstodsacerdoti38 comments

GNU poke is already really promising. You can have a look at this presentation from Kernel Recipes 2019 to get a rough idea of what it looked like ~two years ago:

https://www.youtube.com/watch?v=92Sykut06N8

Think of it as the missing tool between an hex editor and a programming language. Hachoir, Kaitai, linker scripts or most reverse engineering toolkits (radare, etc.) all try to address a similar problem, but from a different angle.

Is this named after the old BASIC command "poke" on micros of the 80s?

This program looks pretty awesome and seems to fit into a use-case that I frequently want. I've usually just consigned myself to using standard hex editors, sometimes little bits of Python to wrangle whatever data I'm trying to manage.

That was the first thing that came to mind for me.

Shouldn't it also have a companion utility named peek?

:-D

If you combime poke and peek you could get "poek" still pronounced poke, and also have a little allusion to elegance by being almost "poet".

Honestly I don't suggest that, just having fun. Simple is good in a name. Then again, so is a unique search term.

Sounds like a better version of the old MS-DOS DEBUG.EXE to me, which for some reason I saw fit to use on explorer.exe on my dad's old WinBook XP running Windows 95 back in the day...

One thing I haven't had much success with when trying editors like this is dealing with variable data, like Pascal-style strings or varints. Another one is a length field that is either one byte, or a NUL byte followed by two bytes, or three NUL bytes followed by four bytes.

I'll have to give this one a try. It would be nice to be able to sift through binary data like bytecode or some non-standard serialization format without writing a one-off utility for it.

I spent a long time looking for something similar to sift through binary files and found this:

https://www.sweetscape.com/010editor/

It lets you write "templates" in a weird hybrid syntax that looks a lot like a C header file but also allows control statements that can decode complicated data structures in a few lines of script. It looks to have very similar capabilities to GNU Poke, but with a GUI.

The poke creator seems to have a very dim view of 010.

Exactly. Much worse syntax choices. Would not want to spend my time with it, when I have much more with 101.

But it least the VM is much faster than 101

https://ide.kaitai.io/ has a yaml syntax, and its online editor has tons of examples.

I recently tried Kaitai for something like this. It worked for some nontrivial cases, but I felt like I kept getting bitten by syntax limitations. All the way through, I kept wondering if writing a one off utility might be faster. But it was possible to express variable structures, sizes and counts. I was using the syntax and the cmd line visualizer, but might have been more productive with their html/gui tooling.

http://kaitai.io/

I skimmed through the manual and from what i can tell this seems to be more of a language (with a REPL) with support for handling data streams (they call them I/O Spaces for some reason) than an editor. There does seem to be support for declaring types of variable length and it is one of the first examples:

    type Packet =
      struct
      {
        byte magic;
        uint<16> length;
        byte[length] data;
      }

It also seems to have optional fields using conditions, using the optional extended header in MP3 id3v2 tag as an example:

    struct ID3V2_Tag =
      struct
      {
        ID3V2_Hdr hdr;
        IDV2_Ext_Hdr ext_hdr if hdr.extended_hdr_present;
      }

(this is an alternative to another way it provides by using unions which work similar to C unions but each alternative also has conditions for when it is valid).

So at least from the above i think it should be possible to declare types that work with variable length and prefixes like that.

It reminded my radare2 when it had just started.

It reminds me of 010 Editor. A programming language to describe structures is exactly what 010 Editor had (they were called “Binary Templates”). It allowed awesome things like: this next sequence of bytes is interpreted differently depending on the previously encountered bytes. For example, here’s the EXE file format: https://www.sweetscape.com/010editor/repository/files/EXE.bt

Can we write data structure libraries? Making a save game editor for old games I like was the first thing that came to mind.

The example in section 1.1.2 Describe-Compute has number of bytes all wrong. I read 4 bytes for 16 bits, 8 for 32 bits...

Gnu has released an editor without including an associated emacs mode? I’m sorry, that’s just not acceptable.

Also no guile scripting.

Did you check? poke-mode.el is part of their source repo:

https://git.savannah.gnu.org/cgit/poke.git/tree/etc/poke-mod...

Yeah. Couldn’t find it. As always, the fastest way to get a correct answer to a question is to post an incorrect one. Thanks.

Oh. I thought it was a free software, federated implementation of Facebook's "poking" feature.

Combining the two (well, the name and your comment) I'd love a poke command that acts like tee but sends a notification when the calling process ends.

  ./backup.sh | poke username

Where username would accept a system user, phone number, email address, webhook url, whatever.

It's not exactly what you describe, but you might find some use in the pv (pipe viewer) command: http://www.ivarch.com/programs/pv.shtml

Is the point of the pipe that the notification should include the output of the command like the following?

  ./backup.sh | ( notify-send "$(cat)" )

though that could also be written:

  notify-send "$(./backup.sh)"

If you also want the output in the terminal, you could use tee:

  ./backup.sh | tee >(notify-send "$(cat)")

If you want it to be an email or SMS, there are probably commands that you could replace notify-send with.

Not really sure with pipe. It could probably just be &&'d with an optional message parameter to be fair.

Or sprinkle some AI on it and decide based on the destination. I wouldn't want a huge log being sent via sms but nbd for email.

> Or sprinkle some AI on it and decide based on the destination.

Or avoid that overcomplication and specify what you want. As the one writing the command, you should know if the output is big and what the ideal is for the destination you want.

Have it specified in a config file, and provide presets for common configurations (e.g. last line and exit code in SMS but full log in email).

You don't have to make it for me haha. This is not a product specification and I am not a demanding customer. It's a hypothetical command that popped into my head while browsing a site with hacker in the name.

It's also a command I could throw together in about an hour with a bit of bash if I really wanted it. Mix in a bit of curl, bit of whatever the sendmail command is these days, bit of Twilio. Job's a good'un.

For the record "sprinkle some AI on it" is if statements, it was a yoke.

It should be reversed:

poke username -- path/to/command arg1 arg2

The command would fork, execute the child, wait for the child to finish, then send out its notification.

This would also allow flags like:

poke --on-failure @koolba -- path/to/foo

Or even handling the child taking too long:

poke --on-lagging 20m @koolba -- path/to/something-that-might-hang

I thought this was clone Yo.

https://slate.com/business/2014/06/marc-andreessen-explains-...

Please, folks, stop posting these "I thought this was going to be about X" comments.

I’m never going to understand why HN frowns upon humor so much.

Me neither. I think the trick is to make it really, really dry and deadpan, then the humourless don't even notice and others have can have a little chuckle.

It's offtopic.

If you don't quash quips it gets all redditty.

Humor is fine. Humor as the only substance of a comment just wastes everyone's time.

Especially when this particular joke is never actually funny.

As I have said before in response to similar comments: HN has no problem with humour. Where it differs from, say, typical reddits is that in order to get upvoted rather than dowvoted, humorous comments have to actually be funny.

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