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Comment by dylan604 | Hacker News Reader

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dylan604

why is JSON ungrepable?

grep key file.json | awk -F: '{print $2}'

if you're already searching for a key, seems like you're just wanting the value.

granted, i hardly ever (have i actually ever??) interact with JSON this way, so i'm not exactly familiar with pitfalls.

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The pitfall is that JSON has zero guarantees for how often line breaks do and don't occur, and is often used to represent hierarchical data. Grepping for 'key: foo', and some liberal use of -A and -B may find you what you're looking for, but grep is simply the wrong tool for that job. (And how do you handle a key with newlines in it?) jq [0] is the right tool, but jq's syntax is it's own, and is harder to use (unless you use it regularly).

[0] https://stedolan.github.io/jq/

when all you have is a hammer, everything looks like a nail. i can see rudimentary attempts at trying to get some data on a system you might not have full control over and are just needing something. i'm sure we've all been logged into a remote system maintained by someone else. cavemen throwing rocks at the spaceship type scenarios.

When it's not formatted, just emitted as a single line.

(Granted grep still works, but...not nicely.)

gotcha. i'm imagining a pretty gnarly regex to return the data after the first colon after the match but only up until the next comma or square bracket or curly bracket. yeah, that's unpleasant.

thankfully, there are tools like jq to help maintain one's sanity

To be honest I find it funny that anyone would attempt to “parse” such a simple format with the wrong tool when there are plenty that can extract data in dot notation.

JSON is greppable if all you need a simple key-value from a known format and indentation. It's much harder if you don't know the indentation/line breaks, or if it's whitespace-free, or if your key can ever appear in your data.

Or just:

    awk -F: '/key/ {print $2}' file.json

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