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Show HN: Bo, the Swiss army knife of data examination and manipulation (github.com)
104 points by kstenerud 8 months ago | hide | past | web | favorite | 19 comments

Example usage from the readme below. There is no explanation whatsoever provided as to what is going on with all the different formats.

    Build up test data for low level code.

    $ bo -n oh1l2 Pc if4b 1.5 1.25 ii2b 1000 2000 3000 ih1 ff fe 7a ib1 10001011
    0x3f, 0xc0, 0x00, 0x00, 0x3f, 0xa0, 0x00, 0x00, 0x03, 0xe8, 0x07, 0xd0, 0x0b, 0xb8, 0xff, 0xfe, 0x7a, 0x8b

What kind of value starts with a lower case ‘o’ or a ‘P’? Or are those commands? If so, why don’t they start with hyphens? Are they file names? If so, why aren’t they preceded by -i or -o to match the docs? Is some of it output?

If I used this, how would I explain my work to my coworkers? A tool should solve problems, not give me a new ones.

My approach is usually to make a tool friendly enough that a newbie can glance at a command typed in by anyone and immediately see what it is supposed to be doing, without reading any help file. But in this case even the help file doesn’t help.

The HN crowd are my UX testers. Whatever people don't understand is easily fixed with a git push!

I'll attempt to possibly convert the grandparent comment into something more constructive. I'd note that your tool is probably the appropriate complexity level compared to utilities of the same sort (ie: sed, awk, dd, etc).

But let's say we want to improve the UX of the tool for new users. As a strawman, you could offer longhand forms of the mode switching flags for them. For example:

bo -n oh1l2 Pc if4b 1.5 1.25 ii2b 1000 2000 3000 ih1 ff fe 7a ib1 10001011

Could be written long-form as:

  bo -n --output=type=hex,width=1,endian=l,width=2 --preset=c --input=type=float,width=4,endian=b 1.5 1.25 --input=type=int,width=2,endian=b 1000 ....
Each of your commands could have an advanced (oh1l2), medium (-o h1l2 or --output h1l2) or beginner (--output=type=hex,width=1,endian=l,width=2) syntax.

You could even print the shorthand version to stderr whenever one of the simpler syntaxes was used.

That's actually another part that fell between the cracks and I'm attempting to address... Aside from the -n, everything is parsed as a whitespace-delimited stream. They just happen to be passed as command line arguments, but they're really just stream data. So all the input, output, formatting, and data commands can be passed as one big string argument

    bo -n "oh1l2 Pc if4b 1.5 1.25 ii2b 1000 2000 3000 ih1 ff fe 7a ib1 10001011"
Or as multiple arguments (no point here, just that you can do it):

    bo -n "oh1l2 Pc if4b 1.5 1.25" "ii2b 1000 2000 3000" "ih1 ff fe 7a ib1 10001011"
Or as a file from disk:

    echo "oh1l2 Pc if4b 1.5 1.25 ii2b 1000 2000 3000 ih1 ff fe 7a ib1 10001011" >mycommands.txt
    bo -n -i mycommands.txt
Or as multiple files from disk:

    echo "oh1l2 Pc if4b 1.5 1.25 ii2b 1000 2000" >mycommands1.txt
    echo "3000 ih1 ff fe 7a ib1 10001011" >mycommands2.txt
    bo -n -i mycommands1.txt -i commands2.txt
Or as stdin:

    echo "oh1l2 Pc if4b 1.5 1.25 ii2b 1000 2000 3000 ih1 ff fe 7a ib1 10001011" | bo -n -i -
Or as a crazy mix of all of that:

    echo "if4b 1.5 1.25" >float-32s.txt
    echo "ii2b 1000 2000 3000" >int-16s.txt
    echo "ih1 ff fe 7a" >hex-bytes.txt
    echo "ib1 10001011" >binary-bytes.txt
    bo -n -i float-32s.txt -i int-16s.txt -i hex-bytes.txt -i binary-bytes.txt oh1l2 Pc
It's designed to fit in with the unix file and pipe paradigm, and also be composeable so that you can have saved data chunks to use in multiple cases, which by necessity makes it a bit opaque for someone approaching it for the first time, but also makes it incredibly powerful when mixed with other unix tools.

You might be interested in docopt (http://docopt.org/), which is a multi-language command line parser that removes almost all of the boiler plate. Whereas the versions of docopts for Python, etc. just require an import, the C version emits C code to do the parsing. It may be worth a look!

It looks like a useful tool, thank you for taking the time to write it.

I realise that further down the page you explain what the various type definitions mean, but it might be nice to make that clear in the initial examples you give.

For instance, say:

    See the per-byte layout (_oh1_) of a larger integer in big (_ih4b_) or little (_ih4l_) endian format, separating each byte with a space (_Ps_).

    $ bo -n oh1 Ps ih4b 12345678
    12 34 56 78
    $ bo -n oh1 Ps ih4l 12345678
    78 56 34 12
It otherwise look a little bit like voodoo to the untrained eye!

Yes, I was a bit torn between showing a bunch of what it can do, and getting so verbose that people stop reading. This tool is surprisingly difficult to explain concisely!

That seems to be a reality of the “Swiss Army Knife for X” products. Tons of features are a blessing and a curse. You should listen to this Masters of Scale episode for an in-depth discussion of how to overcome the inherent marketing challenges: https://mastersofscale.com/diane-greene-look-sideways/

Presumably named for being a selector?

Binary Output

im giggling like a girl because i got ur reference :D

A really needed project! I've started something really similar last year because I felt I needed something: https://github.com/tehmoon/cryptocli which can do a bunch of things. Perhaps you can get ideas!

Needless to say that I use it every day :p

Simple tool, elegant interface!

In the context of large files, do you think you would like to extend it to a multi-threaded variant to fully exploit additional cores or will the overhead due to threading and memory bottlenecks not provide any advantage?

It's fully reentrant and thread safe atm. I haven't thought about multithreaded parsing & printing, though. Mostly it was intended as a quick tool to get data into the right format for testing or debugging or writing code.

This is pretty useful - my shell history is littered with invocations to node (8333..toString(16)) or python (hex(ord('/')) doing this by hand.

Would love to see a homebrew formula for it.

You mean, when under pressure, and used in the wrong way it will suddenly fold up and take a chunk out of its owner?

Thanks for instilling a “fear” of that in me to watch out for when using Swiss knives from now on.

You'll be OK as long as you don't push down on the tip of the blade (imagine trying to use the point to drill a hole in some leather. The blades don't lock, so can fold expectedly.

Other than that, lovely things. I was making a weak joke, which received the downvotes it deserved :)

It's a real threat and happened to me 25 years ago. I still have a scar across the knuckle of my first finger and haven't used a Swiss Army knife since. Leatherman or Gerber only for multi-tools now.

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