How to define a variable in a BASH script by using a JSON file online? Post: 302870263

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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 302870263 by wisecracker on Friday 1st of November 2013 03:12:39 PM

11-01-2013

Registered User

This is a hack but will give you the latest version from the URL you posted.

The command "curl" IS required otherwise the default builtins are used...

Note this is on a Macbook Pro 13 inch, circa August 2012, OSX 10.7.5, Default bash terminal.

I have left the commented out commands so that you can re-edit them in again to see
how it works...

Code:

#!/bin/bash --posix
# OSX 10.7.5, default bash terminal.
# The _json_ version can be virtually anything but must NOT include '"' and ','...
# Obtain the relevant _text_ file.
# NOTE THAT THIS IS A HACK!
curl "https://s3.amazonaws.com/Minecraft.Download/versions/versions.json" > /tmp/jsonfile.dat
# Get the file into a variable...
text=$(cat < /tmp/jsonfile.dat)
# echo "$text"
# Ensure IFS is stored for future rplacement.
ifs_str="$IFS"
IFS=" "
# Use an array as a hack to get to the correct part...
array=($text)
# Check that the file contains the MCVERSION number with extras.
# This assumes that the file format remains the same upon every version.
version=$(echo "${array[5]}")
# echo "$version"
# You now have the version wrapped in inverted commas and a comma too...
# From here you can remove the '"' and ',' using builtins...
MCVERSION=""
decimal=0
subscript=0
length=$[ ${#version} - 1 ]
while [ $subscript -le $length ]
do
	# Remove the inverted commas...
	decimal=$(printf "%d" \'${version:$subscript:1})
	if [ $decimal -eq 44 ]
	then
		break
	fi
	if [ $decimal -eq 34 ]
	then
		subscript=$[ $subscript + 1 ]
	else
		MCVERSION=$MCVERSION${version:$subscript:1}
		subscript=$[ $subscript + 1 ]
	fi
done
# Print the final string...
echo "" 
echo "$MCVERSION"
echo ""
# Replace the original IFS...
IFS="$ifs_str"
# Get the length as a final check...
# length="${#MCVERSION}"
# echo "$length"

The results on this machine...

Code:

Last login: Fri Nov  1 19:03:30 on ttys000
AMIGA:barrywalker~> ./json.sh
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 15240  100 15240    0     0  13546      0  0:00:01  0:00:01 --:--:-- 15179

1.7.2

AMIGA:barrywalker~> _

It is now up to you to modify as required...

Hope it helps...

wisecracker

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LEARN ABOUT DEBIAN

json_write

json::write(3tcl)						       JSON							 json::write(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME

       json::write - JSON generation

SYNOPSIS

       package require Tcl  8.5

       package require json::write  ?1.0.1?

       ::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) 2009-2011 Andreas Kupries <andreas_kupries@sourceforge.net>

json								       1.0.1							 json::write(3tcl)