Or don’t, I’m not your father. The situation Sometimes, you want to get a very specific part of a command output. The classic problem is to get the IP address of an interface. Even today, the results to these queries on your favorite search engine will most likely involve grep, sed, awk and the like. But what if I told you there’s a better way? Using JSON for structuring data Some tools offer outputting their data in JSON format. That data can be processed with the venerable jq utility. The control you have over the processing is higher and the chance that the data format of the output changes is lower. Let’s look at what that means in practice.
  • MonkderVierte@lemmy.ml
    2·
    12 hours ago

    A tradeoff between convenience and usecase. I personally would only use json/jq for complex data processing needs. But then i would use Python, not shell.

    • Laser@feddit.orgOP
      2·
      11 hours ago

      The issue is not only complexity, though it does play a role. You can also run into issues with pure text parsing, especially when whitespace is involved. The IP thing is a very classic example in my opinion, and while whitespace might not be an issue there (more common with filenames), the queries you find online in my opinion aren’t less complex.

      Normal CLI output is often meant to be consumed by humans, so the data presentation requirements are different. Then you find out that an assumption you made isn’t true (e.g. due to LANG indicating a non-English language) and suddenly your matching rules don’t fit.

      There are just a lot of pitfalls that can make things go subtly wrong, which is why parsing general CLI output that’s not intended to be parsed is often advised against. It doesn’t mean that it will go wrong.

      Regarding Python, I think it has a place when you do what I’d call data set processing, while what I talk about is shell plumbing. They can both use JSON, but the tools are probably not the same.

    • Laser@feddit.orgOP
      2·
      15 hours ago

      It’s a cool shell, I like ita lot more since I found out you can use ? to mark a field optional

  • StrangeAstronomer@lemmy.ml
    6·
    1 day ago

    venerable jq

    Ha! jq was the bratty kid I yelled at to get off my lawn. Now he’s a drinking buddy, but still the youngest!

    • Laser@feddit.orgOP
      3·
      17 hours ago

      It’s true that compared to the other utilities, it’s rather new. First release was almost 13 years ago. awk, which I think is the closest comparison, on the other hand turns 50 in 2027… though new awk is only 40.