jo

JO(1)                                                                    JO(1)

NAME
       jo - JSON output from a shell

SYNOPSIS
       jo [-p] [-a] [-B] [-v] [-V] [--] [ [-s|-n|-b] 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 val-
       ues 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.

       When  the := operator is used in a word, the name to the right of := is
       a file containing JSON which is parsed and assigned to the key left  of
       the operator.

TYPE COERCION
       jo's  type  guesses  can be overridden on a per-word basis by prefixing
       word with -s for string, -n for number, or -b for boolean.  The list of
       _word_s  must  be prefixed with --, to indicate to jo that there are no
       more global options.

       Type coercion works as follows:

       word         -s             -n          -b          default
       -----------------------------------------------------------------
       a=           "a":""         "a":0       "a":false   "a":null
       a=string     "a":"string"   "a":6       "a":true    "a":"string"
       a="quoted"   "a":""quot-    "a":8       "a":true    "a":""quot-
                    ed""                                   ed""
       a=12345      "a":"12345"    "a":12345   "a":true    "a":12345
       a=true       "a":"true"     "a":1       "a":true    "a":true
       a=false      "a":"false"    "a":0       "a":false   "a":false
       a=null       "a":""         "a":0       "a":false   "a":null

       Coercing a non-number string  to  number  outputs  the  length  of  the
       string.

       Coercing a non-boolean string to boolean outputs false if the string is
       empty, true otherwise.

       Type coercion only applies to key=value words, and individual words  in
       a -a array.  Coercing other words has no effect.

EXAMPLES
       Create  an  object.  Note how the incorrectly-formatted float value be-
       comes 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  charac-
       ter of value is an open brace or a bracket we attempt to decode the re-
       mainder 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", "false",
       and "null" 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
                 }
              }

       Type coercion:

              $ jo -p -- -s a=true b=true -s c=123 d=123 -b e="1" -b f="true" -n g="This is a test" -b h="This is a test"
              {
                 "a": "true",
                 "b": true,
                 "c": "123",
                 "d": 123,
                 "e": true,
                 "f": true,
                 "g": 14,
                 "h": true
              }

              $ jo -a -- -s 123 -n "This is a test" -b C_Rocks 456
              ["123",14,true,456]

       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"}

       Read element values from a file in order  to  overcome  ARG_MAX  limits
       during object assignment:

              $ ls | jo -a > child.json
              $ jo files:=child.json
              {"files":["AUTHORS","COPYING","ChangeLog" ....

OPTIONS
       jo understands the following global 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 bool-
              ean  elements  true  and false respectively, and "null" as null.
              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 re-
       sults.  If you quote a numeric value, jo will make it a  string.   Com-
       pare 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 mes-
       sage to print, but the output contains garbage anyway.   This  was  de-
       signed thusly.

RETURN CODES
       jo  exits  with a code 0 on success and non-zero on failure after indi-
       cating what caused the failure.

AVAILABILITY
       <http://github.com/jpmens/jo>

CREDITS
       o This program uses json.[ch], by Joseph A.  Adams.

SEE ALSO
       o <https://stedolan.github.io/jq/>

       o <https://github.com/micha/jsawk>

       o <https://github.com/jtopjian/jsed>

       o strtod(3)

AUTHOR
       Jan-Piet Mens <http://jpmens.net>

User Manuals                                                             JO(1)