npm install rjrj is a simple little command line tool and a conceptual fork of jq.
rj allows you to leverage ES6 JS to write handy little command line utilities for processing text, JSON, and more.
I love jq and use it often but after years of use I still struggle to remember the syntax for the more advanced parts of the language.
For me writing anything but a simple jq program requires opening the manual.
This is not jq's fault.
You need practice to get good at something and since jq expression are so short it would take a very long time to become proficient.
I wanted to have a tool just with jq's API (which is rock solid) but with an expression syntax that is more accessible to the JS aficionado.
To install rj simply make sure you have an up to date node (node >= 0.6.x) and use npm:
``bash`
npm i -g rj
This will create two binaries rj and trj.
rj is API equivalent to jq and trj treats input as raw text by default, it is an alias for rj --raw-input --raw-output.
The code you provide to rj is executed once for every entity (line or object) in the input with $ bound to the value, and i to the index.stdout
The result of the last evaluated expression will be edited on the .emit
You can also call a global function (alias e) to emit multiple results.;
To prevent the value of the last expression form being automatically emitted simply terminate your script with .
You can access the bundled in lodash thought the _ global.
Here is a basic example that reads text form a file and numbers every line:
`bash`
rj 'i + ": " + $' some_file.txt
You can affect how rj reads and writes its input and output using some command-line options:
- --version
Output the rj version and exit with zero.
- --help
Print a usage guide.
- --slurp / -s
ToDo: Not working yet
Instead of running the filter for each JSON object in the input, read the entire input stream into a large array and run the filter just once.
- / -R and --json-input / -J --raw-input
With the input wont be parsed as JSON. --slurp
Instead, each line of text is passed to the function as a string.
If combined with , then the entire input is passed to the filter as a single long string.--json-input
is on by default in rj and --raw-input is on by default in trj.--null-input
- / -n
Don't read any input at all!
Instead, the filter is run once using null as the input.
This is useful when using rj as a calculator or to construct JSON data from scratch.
- / -c
By default, rj pretty-prints JSON objects.
Using this option will result in more compact output by instead putting each JSON object on a single line.
-
Use a tab for each indentation level instead of spaces.
-
Use the given number of spaces (no more than 8) for indentation.
- / -C and --monochrome-output / -M
By default, rj outputs colored JSON if writing to a terminal. You can force it to produce color even if writing to a pipe or a file using -C, and disable color with -M.
- / -r / --parsable-output / -p
With , if the emitted result is a string then it will be written directly to standard output rather than being formatted as a JSON parsable string with quotes.--parsable-output
is on by default in rj and --raw-output is on by default in trj.--arg name value
-
This option passes a value to the rj program as a predefined variable.
If you run rj with , then $foo is available as a global and has the value "bar".--arg foo 123
Note that value will be treated as a string, so will bind $foo to "123".--argjson name JSON-text
-
This option passes a JSON-encoded value to the rj program as a predefined variable.
If you run rj with , then $foo is available as a global and has the value {"a": 1}.
When running rj you can expect the following to be defined in context:
- $ - the current inputi
- - the index of the current inputemit()
- / e() - a function that will emit to the output, anything you return will be emitted alsoexec()
- - a function that will execute the parameter synchronously_
- - an instance of lodash_$
- - an instance of _ wrapped $
- - for any argument foo you defied with --arg or --argjson
- The standard JS runtime objects that you would expect like and Math
Here are some examples that demonstrate the use of rj.
`bash`
trj '$.includes("THE") ? $ : undefined' LICENSE
`bash`
rj '$' test/data/edits.json
This is equivalent to jq '.' some_file.json
`bash`
rj -c '$.forEach(e)' test/data/edits.json
This is equivalent to jq -c '.[]' test/data/edits.json`