Tooling Up For JSON

I needed to explore a large (5.7MB) JSON file and my usual command line tools weren’t a good fit.

Casting about I discovered Jshon: Twice as fast, 1/6th the memory. From the home page for Jshon:

Jshon parses, reads and creates JSON. It is designed to be as usable as possible from within the shell and replaces fragile adhoc parsers made from grep/sed/awk as well as heavyweight one-line parsers made from perl/python. Requires Jansson

Jshon loads json text from stdin, performs actions, then displays the last action on stdout. Some of the options output json, others output plain text meta information. Because Bash has very poor nested datastructures, Jshon does not try to return a native bash datastructure as a tpical library would. Instead, Jshon provides a history stack containing all the manipulations.

The big change in the latest release is switching the everything from pass-by-value to pass-by-reference. In a typical use case (processing AUR search results for ‘python’) by-ref is twice as fast and uses one sixth the memory. If you are editing json, by-ref also makes your life a lot easier as modifications do not need to be manually inserted through the entire stack.

Jansson is described as: “…a C library for encoding, decoding and manipulating JSON data.” Usual ./configure, make, make install. Jshon has no configure or install script so just make and toss it somewhere that is in your path.

Under Bugs you will read: “Documentation is brief.”

That’s for sure!

Still, it has enough examples that with some practice you will find this a handy way to explore JSON files.

Enjoy!

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