How to define a variable in a BASH script by using a JSON file online? Post: 302869177

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Top Forums Shell Programming and Scripting How to define a variable in a BASH script by using a JSON file online? Post 302869177 by nbsparks on Tuesday 29th of October 2013 05:47:52 PM

10-29-2013

Registered User

How to define a variable in a BASH script by using a JSON file online?

Hello,

I would like to modify an existing script of mine that uses a manually defined "MCVERSION" variable and make it define that variable instead based on this JSON file stored online:
https://s3.amazonaws.com/Minecraft.D.../versions.json

Within that JSON, I 'm looking for this information:

Code:

{
  "latest": {
    "snapshot": "1.7.2",
    "release": "1.7.2"
  },

I want $MCVERSION to equal the "latest/release" value above (in this case, MCVERSION=1.7.2). I'm perfectly OK with pulling the JSON file down locally first via "wget" command. In fact, I'd prefer that so I can reference it if needed if my script fails (in case they change their JSON file format).

Here is my script (not that it matters too much for this example, I doubt).

Code:

#!/bin/bash

#### Define the current version of Minecraft
MCVERSION=1.7.2

#### Remove any current versions and create new folder for the JAR file
cd /home/mcmaps/.minecraft/versions
rm * -rf
mkdir $MCVERSION
cd /home/mcmaps/.minecraft/versions/$MCVERSION/

#### Download fresh copy of Minecraft JAR file for use of textures
wget https://s3.amazonaws.com/Minecraft.Download/versions/$MCVERSION/$MCVERSION.jar -P ~/.minecraft/versions/$MCVERSION/

Currently, the script results in creating this file:
/home/mcmaps/.minecraft/versions/1.7.2/1.7.2.jar

The goal is to do that without ever having to manually modify the MCVERSION variable in this script.

nbsparks

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LEARN ABOUT MOJAVE

json_write

json::write(n)							       JSON							    json::write(n)

__________________________________________________________________________________________________________________________________________________

NAME

       json::write - JSON generation

SYNOPSIS

       package require Tcl  8.5

       package require json::write  ?1?

       ::json::write indented

       ::json::write indented flag

       ::json::write aligned

       ::json::write aligned flag

       ::json::write string s

       ::json::write array arg...

       ::json::write object key value...

_________________________________________________________________

DESCRIPTION

       The  json::write package provides a simple Tcl-only library for generation of text in the JSON http://www.json.org/ data exchange format as
       specified in RFC 4627 http://www.ietf.org/rfc/rfc4627.txt.

COMMANDS

       ::json::write indented
	      This method returns the current state of the indentation setting.

       ::json::write indented flag
	      This and the method aligned configure the layout of the JSON generated by the package.

	      If this flag is set (default) the package will break the generated JSON code across lines and  indent  it  according  to	its  inner
	      structure, with each key of an object on a separate line.

	      If this flag is not set, the whole JSON object will be written on a single line, with minimum spacing between all elements.

       ::json::write aligned
	      This method returns the current state of the alignment setting.

       ::json::write aligned flag
	      This and the method indented configure the layout of the JSON generated by the package.

	      If  this flag is set (default) the package ensures that the values for the keys in an object are vertically aligned with each other,
	      for a nice table effect. To make this work this also implies that indented is set as well.

	      If this flag is not set, the output is formatted as per the value of indented, without trying to align the values for object keys.

       ::json::write string s
	      This method takes the string s and returns it properly quoted for JSON as its result.

       ::json::write array arg...
	      This method takes a series of JSON formatted arguments and returns them as a properly formatted JSON array as its result.

       ::json::write object key value...
	      This method takes a series of key/value arguments, the values already formatted for JSON, and returns them as a  properly  formatted
	      JSON object as its result, with the keys formatted as JSON strings.

BUGS, IDEAS, FEEDBACK
       This  document, and the package it describes, will undoubtedly contain bugs and other problems.	Please report such in the category json of
       the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883].  Please also report any ideas for enhancements you  may  have  for
       either package and/or documentation.

KEYWORDS

       data exchange, exchange format, javascript, json

CATEGORY

       CGI programming

COPYRIGHT

       Copyright (c) 2009 Andreas Kupries <andreas_kupries@sourceforge.net>

json									1.0							    json::write(n)