[vog]

The so-called "plain text formats" are also just representations of complex objects. Often these formats are ad-hoc and hard to parse correctly. Multiple text files in a file system hierarchy (e.g. /etc) are also just nested structures.

So in principle, treating those as complex object structures is the right way to go. Also, I believe this is the idea behind D-Bus and similar modern Unix developments.

However, what's hard is to provide good tooling with a simple syntax that is simple to understand:

* Windows Registry and Power Shell show how not to do it.

* The XML toolchain demonstrate that any unnecessary complexity in the meta-structure will haunt you through every bit of the toolchain (querying, validation/schema, etc.).

* "jq" goes somewhat into the right direction for JSON files, but still hasn't found wide adoption.

This appears to be a really hard design issue. Also, while deep hierarchies are easier to process by scripts, a human overview is mostly achieved by advances searching and tags rather than hierarchies.

A shell needs to accomodate for both, but maybe we really just need better command line tools for simple hierarchial processing of arbitrary text file formats (ad-hoc configs, CSV, INI, JSON, YAML, XML, etc.).

[vidarh]

I lean towards wanting all my tools to support at least one common structured format (and JSON generally would seem the best supported) these days. It'd be great if there was a "standard" environment variable to toggle JSON input/output on for apps. If you did that, then e.g. a "structured" shell could just default to turning that on, and try detecting JSON on output and offering according additional functionality.

That'd be a tolerable graduated approach where you get benefits even if not every tool support it.

With "jq", I'm already increasingly leaning on JSON for this type of role.

It'd need to be very non-invasive, though, or all kinds of things are likely to break.

[skissane]

I wish there was a way for pipes to carry metadata about the format of the data being passed over the pipe, like a MIME type (plain text, CSV, JSON, XML, etc). Ideally with some way for the two ends of the pipe to negotiate with each other about what types each end supports. I think that sort of out-of-band communication would most likely need some kernel support.

Maybe an IOCTL to put a pipe into "packet mode" in which rather than just reading/writing raw bytes you send/receive Type-Length-Value packets... If you put your pipe in packet mode, and the other end then reads or writes without enabling packet mode, the kernel can send a control message to you saying "other end doesn't support packet mode" and then you can send/receive data in your default format. Whereas, if both ends enter packet mode before reading/writing, then the kernel sends a control message to one end saying "packet mode negotiated", and which triggers the two ends to exchange further control messages to negotiate a data format, before actually sending the data. (This implies pipes must be made bidirectional, at least for control packets.)

[zdkl]

As counterpoint if only for the sake of my wetware memory, I'd rather have only a few pipes being as agnostic and generally capable as possible than complex plumbing.

I don't mean to argue there is no value in specialised adapters, but I believe the default should be as general as can be. Let me worry about parsing/formats at the application level and get me simple underlying pipes. If I need something specific I should be prepared to dig into docs and find out what I need anyway, so default text vs install or explicitely configure your system to use something else seems like a sane feature/complexity segregation in the general case.

EDIT: good quote from another thread to illustrate my point: > Removing the responsibility for reliable communication from the packet transport mechanism allows us to tailor reliability to the application and to place error recovery where it will do the most good. This policy becomes more important as Ethernets are interconnected in a hierarchy of networks through which packets must travel farther and suffer greater risks.

replace Ethernet with pipes and the point still has merit IMO. Lifted off of https://news.ycombinator.com/item?id=14675115

[Too]

Programs can determine if the receiving output is a TTY or not and enable e.g. colored output accordingly, sounds like something similar.

[valarauca1]

This is called a "Unix Domain Socket" they're 20+ years old.

[vram22]

It's an innovative and interesting idea. But just to play devil's advocate for a minute, for this to get widespread uptake, the way it is implemented would have to be agreed on as being the right way, by a lot of people (i.e. users). And there could be lots of different ways of implementing what you describe, with variations, which makes it more difficult (though not impossible) to get accepted widely, compared to the existing plain pipes and passing data as text around between commands, because not much variation is possible there.

[jtolmar]

I'd prefer a "crash if receiver doesn't support sender's MIME type" model for debugability.

Which could still be ergonomic if all the common piping programs supported some specific collection of formats and there was a relatively robust format-converting program.

[ori_b]

> It'd be great if there was a "standard" environment variable to toggle JSON input/output on for apps.

Look at FreeBsd's libxo. It's supported by most of the base system.

[drothlis]

It looks like libxo does the output in structured format, but what about input? (For chaining commands together with pipes). Did the FreeBsd porting work[1] implement the input side with libxo, independently of libxo, or not at all?

(Not to diminish libxo --it looks pretty cool, and I didn't know about it before-- just curious.)

[1]: https://wiki.freebsd.org/LibXo

[floatboth]

On the input side, FreeBSD prefers libucl https://github.com/vstakhov/libucl

[mioelnir]

I don't think input meant configuration file syntax here, but actual

    echo $somejson-jobspec | ifconfig

instead of

    ifconfig em0 inet 192.02.1/24 alias

[vidarh]

That looks very interesting, though I actually think that standardising on the command-line/env variable API is more important than an implementation. It's the moment you can "automagically" "upgrade" a pipe to contain structured data for apps that support it that you get the most value.

But given that it's there, I'll certainly consider it when writing tools, and consider supporting the command-line option/env var even if/when I don't use the implementation...

[ibotty]

Amazing! I did not know that.

[vog]

Nice idea! Maybe this issue is similar to that of command completion, but could also result in a similar mess. Every command has its "-h" or "--help", showing the syntax, available options and so on. But since even that is not really standardized, separate command-line completion rules are written for every command. And for every shell.

[skissane]

Define a standard format for describing command syntax. I'd suggest basing it on JSON, but you could use XML or Protobuf or Thrift or ASN.1 or Sexprs or whatever. Embed in executables a section containing the command syntax description object. Now when I type in a command, the shell finds the executable on the path, opens it, locates the command description syntax section (if present), and if found uses that to provide tab completion, online help, smarter syntax checking, whatever–if you've ever used OS/400, it has a feature where it constructs a fill-in-form dialog based on the command syntax descriptions, which you can call up at the press of a function key. (Obviously the shell should cache this data, it shouldn't reread /bin/ls every time I type "ls".)

[jstimpfle]

There isn't a 1:1 mapping of binaries to documentation or completion scripts. That idea won't work out.

"Defining a standard format" hasn't been a successful practice in the Unix world. Many standards consist essentially of the bare minimum that everybody can agree with.

Unix command-line interfaces are already structured (as a list of strings), and more structure would be hard to support at the binary level. There are too many possibilities of doing that, and most CLI programs wouldn't even need that.

[yorwba]

If the binary is using one of a few common libraries, e.g. GNU getopt, to read its command-line parameters, it should be possible to extract somewhat useful completions automatically.

Then you are essentially relying on the de-facto standard of not rolling your own argument parsing, as opposed to some product of a standards committee.

[johnny22]

fish shell does it with manpages https://fishshell.com/docs/current/commands.html#fish_update...

[jstimpfle]

Getopt is just barely flexible enough to be applicable to many projects while still encoding some conventions (dash-prefixed options and optional arguments).

Still it's too opinionated to be applicable to all programs. And it's by far not structured enough to support automated completions.

Every programmer goes through this phase of trying to abstract what can't be abstracted. Essentially for non-trivial programs you need to encode what you want yourself. You can't write a library that is suitable for the infinitely many thinkable programs.

By the way, even handcoded completions are, often enough, more confusing than helpful to me (and not because they are handcoded). I've disabled them entirely.

[solidsnack9000]

This is actually a very interesting problem. The format would be an IDL, since you're describing a "struct" of options, array-valued fields, and "typed" fields that are constrained to certain grammars (numbers, &c.).

[ams6110]

This sort of exists. The command syntax format is the standard man page "Usage" and "Options" sections, and an implementation is docopt (http://docopt.org/)

[vidarh]

I still miss AmigaOS, where command options parsing was largely standardised ca. 1987 via ReadArgs() (barring the occasional poor/direct port from other OS's) [1]. It wasn't perfect (it only provided a very basic usage summary), but it was typed, and it was there.

[1] http://www.pjhutchison.org/tutorial/cmdline_arrgs.html

[pjmlp]

If it was only that, what about libraries for handling all kinds of file formats via the OS plugin system?

[vidarh]

There are lots of things I miss. Datatypes is definitively one of them. AREXX ports everywhere (I hate the language, but you don't need the language to make use of AREXX ports; Dbus is like what you get if you take AREXX and give it to a committee; the beauty of AREXX was the sheer simplicity that made it so trivial to add support for it to "everything" to the extent that many tools built their central message loop around checking for AREXX commands and built their application around dispatching AREXX like commands between different parts of the app).

Assigns is another one (for the non-Amiga aware that stumble on this, on the Amiga, I'd refer to my files with "Home:", but unlike on a Unix/Linux, Home: is not an environment variable that needs to be interpreted like $HOME or something that needs to be expanded like "~" - it is recognised by the OS as a valid filesystem path, assigned at runtime; similarly, instead of having a $PATH that needs to be interpreted, all my binaries would be accessible via "C:" for "command" - "C:" is an assign made up of multiple actual directories, one of which would typically be Sys:C, where Sys: is the System volume, and Sys: itself is an assign pointing to whatever drive you booted; Assigns are like dynamic symlinks with multiple targets, or like $PATH's interpreted by the OS)

[codesnik]

jq is awesome. "json lines" data format (where each record is json without literal newlines, and newline separates records) nicely upgrades unix pipes to structured output, so you can mix old unix tools, like head, tail etc with jq. maybe what's needed is some set of simple json wrappers around core utils to increase adoption.

[subnixr]

> "json lines" data format (where each record is json without literal newlines, and newline separates records)

Good point, but jq handles this already. If the payload is an array of object, simply `jq -c '.[]'` to get an object per line

[gregopet]

jq can't handle big numbers, it silently mangles them, beware! Was bitten by this twice already..

[kemayo]

That's per the spec[1], enjoyably:

    Note that when such software is used, numbers that are
    integers and are in the range [-(2**53)+1, (2**53)-1]
    are interoperable in the sense that implementations will
    agree exactly on their numeric values.

2^53 is only 9007199254740990, so it's not too hard to exceed that, particularly in things like twitter status ids.

The recommended use is to have big numbers as strings, since it's the only way to reliably pass them around. (Yes, this is kind of horrible.)

[1]: https://tools.ietf.org/html/rfc7159#section-6

[falcolas]

I have to admit, I was not familiar with this limitation. Thanks for pointing it out.

And I'd go from "kind of horrible" to just "horrible".

Integral bit limits are an implementation detail that every language has a way to overcome - they shouldn't be built into an encoding spec.

[kemayo]

Again, not saying this is a good thing, but it's an understandable consequence of the standardization partially involving "let's document how the browsers existing JS implementations deal with running eval on a string". It's easier to write the standard so that existing implementations fit it, rather than requiring changes from everyone.

[falcolas]

I imagine it depends on your aims. If your aim is just to document existing behavior, that's one thing. But if your aim is to create a new, simple, data interchange format, documenting existing implementations is only going to limit its usefulness. It could have forced the current implementations fixed instead of setting the bar.

As pointed out upstream, we're dealing with a lot of data these days, and such limitations will only cause JSON to become marginalized or complicated with implementation-dependent workarounds, like integers in strings.

[fnord123]

>A shell needs to accomodate for both, but maybe we really just need better command line tools for simple hierarchial processing of arbitrary text file formats (ad-hoc configs, CSV, INI, JSON, YAML, XML, etc.).

Start with record based streams first. Text streams requires [buggy] parsing to be implemented everywhere. It should be possible to have escaped record formats that allow the right side of the pipe to use AWK style $1, $2, $3, etc.

After removing the need to parse the fields, the next priority, imo, would be to introduce integral types so the actual data itself doesn't need to be parsed. u32 on the LHS can just be 4 bytes and then read out on the RHS as 4 bytes. This could save a lot of overhead when processing large files.

Only then would I want to get into hierarchies, product types, sum types, etc.

[moe]

This is dead on.

Half of all parsing work consists of splitting things into records, by lines, delimiters or whitespace. That's where the great escaping headache begins.

In a better shell the following command would Just Work™:

> find | rm %path/%filename

[int_19h]

Powershell does two things right: it uses structured output, and it separates producing the data from rendering the data.

It also does one thing wrong: it uses objects (i.e. the stuff that carries behavior, not just state). This ties it to a particular object model, and the framework that supports that model.

What's really needed is something simple that's data-centric, like JSON, but with a complete toolchain to define schemas and perform transformations, like XML (but without the warts and overengineering).

[still_grokking]

> What's really needed is something simple that's data-centric, like JSON, but with a complete toolchain to define schemas and perform transformations, like XML (but without the warts and overengineering).

What would it be? Is there a real alternative to XML with those features out there? I don't think so.

When you would want to have the features of XML and would design it from scratch I'm quite sure it would have the complexity of XML again.

Usually implementing some functionality yields every time the same level of complexity regardless of how you implement it (given that none of the implementations isn't out right stupid of curse).

[int_19h]

> When you would want to have the features of XML and would design it from scratch I'm quite sure it would have the complexity of XML again.

I don't think so. The problem with the XML stack is that it has been designed with some very "enterprisey" (for the lack of better term) scenarios in mind - stuff like SOAP. Consequently, it was all design by committee in the worst possible sense of the word, and it shows.

To see what I mean, take a look at XML Schema W3C specs. That's probably the worst part of it, so it should be readily apparent what I mean:

https://www.w3.org/TR/xmlschema11-1/ https://www.w3.org/TR/xmlschema11-2/

The other problem with XML is that it's rooted in SGML, and inherited a lot of its syntax and semantics, which were designed for a completely different use case - marking up documents. Consequently, the syntax is overly verbose, and some features are inconsistent for other scenarios - for example, if you use XML to describe structured data, when do you use attributes, and when do you use child elements? Don't forget that attributes are semantically unordered in XDM, while elements are ordered, but also that attributes cannot contain anything but scalar values and arrays thereof.

Oh, and then don't forget all the legacy stuff like DTD, which is mostly redundant in the face of XML Schema and XInclude, except it's still a required part of the spec.

I guess the TL;DR version of it is that XML today is kinda like Java - it was there for too long, including periods when our ideas of best practices were radically different, and all that was enshrined in the design, and then fossilized in the name of backwards compatibility.

One important takeaway from XML - why it was so successful, IMO - is that having a coherent, a tightly bound spec stack is a good thing. For example, with XML, when someone is talking about schemas, you can pretty much assume it's XML Schema by default (yes, there's also RELAX NG, but I think calling it schema is a misnomer, because it doesn't delve much into semantics of what it describes - it's more of a grammar definition language for XML). To transfer XML, you use XSLT. To query it, you use XPath or XQuery (which is a strict superset). And so on. With JSON, there's no such certainty.

The other thing that the XML stack didn't quite see fully through, but showed that it could be a nice thing, is its homoiconicity: e.g. XML Schema and XSLT being XML. Less so with XPath and XQuery, but there they had at least defined a canonical XML representation for it, which gives you most of the same advantages. Unfortunately, with XML it was just as often a curse as it was a blessing, because of how verbose and sometimes awkward its syntax is - anyone who wrote large amounts of XSLT especially knows what I'm talking about. On the other hand, at least XML had comments, unlike JSON!

Hey, maybe that's actually the test case? A data representation language must be concise enough, powerful enough, and flexible enough to make it possible to use it to define its own schema and transformations, without it being a painful experience, while also being simple enough that a single person can write a parser for it in a reasonable amount of time.

[wtetzner]

> A data representation language must be concise enough, powerful enough, and flexible enough to make it possible to use it to define its own schema and transformations, without it being a painful experience, while also being simple enough that a single person can write a parser for it in a reasonable amount of time.

Seems like a standardized S-expression format would fit the bill.

You could even try to make it work with existing XML tools by specifying a way to generate XML SAX events from the S-expressions.

[int_19h]

I'd prefer a format that distinguishes between sequences and associative arrays a bit more clearly. You can do that with S-exprs with some additional structure imposed on top, but then that gets more verbose than it has to be.

JSON is actually pretty decent, if only it had comments, richer data types, and some relaxed rules around syntax (e.g. allow trailing commas and unquoted keys).

[wtetzner]

Maybe something like EDN? https://github.com/edn-format/edn

[skywhopper]

The brilliant thing about the status quo is that it already does accomodate both line-based and structured pipelines. There's no reason we should expect to use the same set of commands for both purposes. In fact, we most definitely shouldn't. A tool like jq is a great example of this: it works great for JSON, and it doesn't attempt to do more. When we want to work with JSON in a pipeline, we pull out jq. When we want to work with XML, we pull out xmlstarlet or the like. When we want to work with delimited columnar data, we can use awk or cut. I'm failing to see what's missing from an architectural point of view.

[zdkl]

> in principle, treating those as complex object structures is the right way to go

I do not see this as a given. It's a matter of abstraction vs performance tradeoff and that is highly subjective. Unless you pioneer a new standard form for complex object notation this'll just end up back to a format flamewar.

(And if we go that way, I'd argue for s-exprs or -dare I say it- xml)

[mos_basik]

On phone so unsure if it's been mentioned in the thread already, but I've been enjoying learning a js library JSONata [0] after finding it included in Node-RED.

I remember finding jq a few weeks ago and thinking "wow, this will probably come in handy for a specific kind of situation" and filing it mentally for later use, but I haven't used it for anything yet so I'm not super familiar with the extent of it's features.

I have been using a lot of JSONata one liners to replace several procedural functions that were doing data transforms on JSON objects, and I'm very impressed. It's a querying library but it's Turing complete - it has lambdas, it can save references to data and functions as variables, etc.

It also seems relatively new/unknown; I've found hardly any blogs or forums mentioning it. The developer is active - he fixed a bug report I submitted in less then a day.

I'd love to have that kind of functionality in a CLI tool. Maybe jq is equally powerful, I don't know.

I haven't had time to run any performance analysis on JSONata and haven't found anyone else online who's done any yet. I'm very curious how its queries compare to efficiently implemented procedural approaches.

0: http://jsonata.org/

[elcritch]

Thanks! Will have to try out `jsonata`, as `jq` never clicked for me (too complex). Alternately I've been using a node.js program `json` [1] which has a basic but straightforward cli which covers 95% of my daily needs. I believe I found after trying to figure out the tool Joyent.com uses in there SmartOS sysadmin setup. Not sure if it's the exact same tool, but it's very similar.

As an example, basic manipulation is just:

`echo '{"age":10}' | json -e 'this.age++' #=> {"age": 11}`

1: https://github.com/trentm/json

[still_grokking]

For XML there are xml-coreutils[1].

[1] http://www.lbreyer.com/xml-coreutils.html

[merb]

btw. one of my favorite config is HOCON. it allows ini style and json style.https://github.com/typesafehub/config/blob/master/HOCON.md

[agumonkey]

sexp ?

ps: I kinda like powershell (the few hours I toyed in it

[eecc]

S-expressions