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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jigdo-lite

JIGDO-LITE(1)															     JIGDO-LITE(1)

NAME

       jigdo-lite - Download jigdo files using wget

SYNOPSIS

       jigdo-lite [ URL ]

DESCRIPTION

       See jigdo-file(1) for an introduction to Jigsaw Download.

       Given  the  URL	of  a  `.jigdo' file, jigdo-lite downloads the large file (e.g. a CD image) that has been made available through that URL.
       wget(1) is used to download the necessary pieces of administrative data (contained in the `.jigdo' file	and  a	corresponding  `.template'
       file) as well as the many pieces that the large file is made from. The jigdo-file(1) utility is used to reconstruct the large file from the
       pieces.

       `.jigdo' files that contain references to Debian mirrors are treated specially: When such a file is recognized, you are asked to select one
       mirror out of a list of all Debian mirrors.

       If  URL	is not given on the command line, the script prompts for a location to download the `.jigdo' file from. The following command line
       options are recognized:

       -h --help
	      Output short summary of command syntax.

       -v --version
	      Output version number.

       --scan FILES
	      Do not ask for "Files to scan", use this path.

       --noask
	      Do not ask any questions, instead behave as if the user had pressed Return at all prompts. This can be useful  when  running  jigdo-
	      lite from cron jobs or in other non-interactive environments.

SEE ALSO

       jigdo-file(1), jigdo-mirror(1), wget(1) (or `info wget')

       CD images for Debian Linux can be downloaded with jigdo <URL:http://www.debian.org/CD/jigdo-cd/>.

AUTHOR

       Jigsaw  Download  <URL:http://atterer.net/jigdo/>  was written by Richard Atterer <jigdo atterer.net>, to make downloading of CD ROM images
       for the Debian Linux distribution more convenient.

								    19 May 2006 						     JIGDO-LITE(1)