jc – JSONifies the output of many CLI tools

Re:jc – JSONifies the output of many CLI tools by rob74 on Thursday November 03, 2022 @05:14AM (#33448677)

Great idea, but sounds like a maintenance nightmare to me. Not only that many users will complain that their favorite CLI tool isn't supported, but also a new release of any of the supported CLI tools might break the support without any kind of warning, as I don't think changes to the (human-readable) output are considered major changes.

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Re:jc – JSONifies the output of many CLI tools by vidarh on Thursday November 03, 2022 @05:31AM (#33448797)

Changes to the human-readable output of most standard Unix tools are a big deal given the amount of scripts which depends on them. They commonly are seen as fairly stable to the point that even some non-Posix tools like e.g. apt, which doesn't have a stable CLI warns about it to stderr if you try to redirect it's output to a pipe[1].

If anything, though, that's a good reason for a tool like this to exist rather than have every script that depends on these tools use their own, often hacky, parsing of the output.

[1] "WARNING: apt does not have a stable CLI interface. Use with caution in scripts."

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Re:jc – JSONifies the output of many CLI tools by slightwinder on Thursday November 03, 2022 @08:14AM (#33449848)

It doesn't even need a new release. jc can already fail because of details like the system-language. With my local language, on a simple output of ls -l, it's parsing

    {"filename":"drwxr-xr-x  16 root root    4096 Oct  4 11:21 ."}

instead of

    {"filename":".","flags":"drwxr-xr-x","links":16,"owner":"root","group":"root","size":4096,"date":"Oct 4 11:21"}

with LANG=US. This makes it really hard to trust such a tool.

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Re:jc – JSONifies the output of many CLI tools by simonkagedal on Thursday November 03, 2022 @01:21PM (#33454295)

This is true. However, the issue is with the tool outputting unstructured data to begin with. As the `jc` author says, the best would be if tools supported structured output formats to begin with.

Any custom parser of ls output would potentially have the same problem. Of course, it can be improved though – for example by looking at LANG – and it would be nice for such improvements to get into `jc`, so that other tools can rely on it at least more than doing the parsing directly themselves.

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Re:jc – JSONifies the output of many CLI tools by kbrazil on Thursday November 03, 2022 @06:46PM (#33459015)

Hi there! `jc` author here. Yes, it is a documented caveat[0] that the `C` or `en_US.UTF-8` locales should be used for best results.

It's not unheard of for tools to require `C` locale for proper parsing:

    $ LC_ALL=C ls -l | jc --ls

This is one of many inherent issues with using unstructured text as an API. That's why I believe there should be a JSON (or at least some other widely used format[1]) option for tools that have output that would be useful in scripts.

[0] https://github.com/kellyjonbrazil/jc#locale

[1] formats should have good library support across many languages and nice filter/query capabilities from the command-line

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