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NAME
====
jo - JSON output from a shell
SYNOPSIS
========
jo [-p] [-a] [-B] [-v] [-V] [word ...]
DESCRIPTION
===========
*jo* creates a JSON string on *stdout* from *word*s given it as
arguments or read from *stdin*. Without option `-a` it generates an
object whereby each *word* is a `key=value` (or `key@value`) pair with
*key* being the JSON object element and *value* its value. *jo* attempts
to guess the type of *value* in order to create number (using
*strtod(3)*), string, or null values in JSON.
*jo* treats `key@value` specifically as boolean JSON elements: if the
value begins with `T`, `t`, or the numeric value is greater than zero,
the result is `true`, else `false`. A missing or empty value behind the
colon results in a `null` JSON element.
*jo* creates an array instead of an object when `-a` is specified.
EXAMPLES
========
Create an object. Note how the incorrectly-formatted float value becomes
a string:
$ jo tst=1457081292 lat=12.3456 cc=FR badfloat=3.14159.26 name="JP Mens" nada= coffee@T
{"tst":1457081292,"lat":12.3456,"cc":"FR","badfloat":"3.14159.26","name":"JP Mens","nada":null,"coffee":true}
Pretty-print an array with a list of files in the current directory:
$ jo -p -a *
[
"Makefile",
"README.md",
"jo.1",
"jo.c",
"jo.pandoc",
"json.c",
"json.h"
]
Create objects within objects; this works because if the first character
of value is an open brace or a bracket we attempt to decode the
remainder as JSON. Beware spaces in strings ...
$ jo -p name=JP object=$(jo fruit=Orange hungry@0 point=$(jo x=10 y=20 list=$(jo -a 1 2 3 4 5)) number=17) sunday@0
{
"name": "JP",
"object": {
"fruit": "Orange",
"hungry": false,
"point": {
"x": 10,
"y": 20,
"list": [
1,
2,
3,
4,
5
]
},
"number": 17
},
"sunday": false
}
Booleans as strings or as boolean (pay particular attention to *switch*;
the `-B` option disables the default detection of the "`true`" and
"`false`" strings):
$ jo switch=true morning@0
{"switch":true,"morning":false}
$ jo -B switch=true morning@0
{"switch":"true","morning":false}
Elements (objects and arrays) can be nested. The following example nests
an array called *point* and an object named *geo*:
$ jo -p name=Jane point[]=1 point[]=2 geo[lat]=10 geo[lon]=20
{
"name": "Jane",
"point": [
1,
2
],
"geo": {
"lat": 10,
"lon": 20
}
}
Read element values from files: a value which starts with `@` is read in
plain whereas if it begins with a `%` it will be base64-encoded:
$ jo program=jo authors=@AUTHORS
{"program":"jo","authors":"Jan-Piet Mens <jpmens@gmail.com>"}
$ jo filename=AUTHORS content=%AUTHORS
{"filename":"AUTHORS","content":"SmFuLVBpZXQgTWVucyA8anBtZW5zQGdtYWlsLmNvbT4K"}
OPTIONS
=======
*jo* understands the following options.
-a
: Interpret the list of *words* as array values and produce an array
instead of an object.
-B
: By default *jo* interprets the strings "`true`" and "`false`" as
boolean elements `true` and `false` respectively. Disable with this
option.
-p
: Pretty-print the JSON string on output instead of the terse one-line
output it prints by default.
-v
: Show version and exit.
-V
: Show version as a JSON object and exit.
BUGS
====
Probably.
If a value given to *jo* expands to empty in the shell, then *jo*
produces a `null` in object mode, and might appear to hang in array
mode; it is not hanging, rather it's reading *stdin*. This is not a bug.
Numeric values are converted to numbers which can produce undesired
results. If you quote a numeric value, *jo* will make it a string.
Compare the following:
$ jo a=1.0
{"a":1}
$ jo a=\"1.0\"
{"a":"1.0"}
Omitting a closing bracket on a nested element causes a diagnostic
message to print, but the output contains garbage anyway. This was
designed thusly.
RETURN CODES
============
*jo* exits with a code 0 on success and non-zero on failure after
indicating what caused the failure.
AVAILABILITY
============
<http://github.com/jpmens/jo>
CREDITS
=======
- This program uses `json.[ch]`, by Joseph A. Adams.
SEE ALSO
========
- <https://stedolan.github.io/jq/>
- <https://github.com/micha/jsawk>
- strtod(3)
AUTHOR
======
Jan-Piet Mens <http://jpmens.net>
|
