batch file, read json file into string

Question

I need to read a json file:

{
   "key": {
       "subkey": "value"
   }
}

so I can pass it as an argument to a command:

program -e SETTINGS=<JSON FILE AS STRING>

Before trying to automate this I'd check if it works with a condensed string like this with escaped inner double quotes program -e "SETTINGS={\"key\":{\"subkey\": \"value\"}}" — user6811411
– user6811411, Commented Sep 16, 2017 at 15:15

zett42 · Accepted Answer · 2017-09-18 07:16:35Z

4

Combining the answers to these questions...

... we can write the following batch file:

:: Make it possible to read immediate value of variable using !variable! syntax.
setlocal enabledelayedexpansion

:: Read file "test.json" into variable data, removing line breaks.
set data=
for /f "delims=" %%x in (test.json) do set "data=!data!%%x"

:: Escape double quotes in data
set data=%data:"=\"%

:: Finally call program with the entire content of the JSON file as parameter
program -e "SETTINGS=%data%"

Note that when using the cmd.exe command processor, the maximum length for a commandline and also for environment variables is 8191 characters, so this will obviously restrict the maximum size of the JSON file you can pass.

edited Sep 18, 2017 at 7:16

answered Sep 16, 2017 at 20:03

zett42

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1 Comment

dbenham Over a year ago

Your length limit is misleading / not relevant - batch is further restricted to 8191 max length for variables and also for command lines.

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