How to write JSON file using Bash?

Question

I'd like to write a JSON file using BASH but it seem's not working well..

My code :

sudo echo -e "Name of your app?\n"
sudo read appname
sudo cat "{apps:[{name:\"${appname}\",script:\"./cms/bin/www\",watch:false}]}" > process.json

Issue : -bash: process.json: Permission denied

have you checked you have permission to create a file at specified location ? — Hemant Metalia, Oct 06 '16 at 12:28
`sudo echo` and `sudo read` on the first two lines look completely pointless to me — Tom Fenech, Oct 06 '16 at 12:29
`vim` opens the file; with `> process.json`, the *shell* opens the file before `sudo` actually runs. — chepner, Oct 06 '16 at 12:32
Possible duplicate of [Output JSON from Bash script](https://stackoverflow.com/q/12524437/608639) — jww, Jun 22 '19 at 18:19

chepner · Answer 1 · 2021-09-17T16:59:18.770

31

Generally speaking, don't do this. Use a tool that already knows how to quote values correctly, like jq:

jq -n --arg appname "$appname" '{apps: [ {name: $appname, script: "./cms/bin/www", watch: false}]}' > process.json

That said, your immediate issues is that sudo only applies the command, not the redirection. One workaround is to use tee to write to the file instead.

echo '{...}' | sudo tee process.json > /dev/null

edited Sep 17 '21 at 16:59

answered Oct 06 '16 at 12:29

chepner

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Cannot make it an edit because that requires at least 6 characters, but the backtick after `false}]}` should be replaced with standard tick to work properly: `jq -n --arg appname "$appname" '{apps: [ {name: $appname, script: "./cms/bin/www", watch: false}]}' > process.json ` – datapug Sep 17 '21 at 15:41
Thank you, it's fixed now. – chepner Sep 17 '21 at 16:59

score 12 · Answer 2 · answered Oct 06 '16 at 12:28

To output text, use echo rather than cat (which outputs data from files or streams).

Aside from that, you will also have to escape the double-quotes inside your text if you want them to appear in the result.

echo -e "Name of your app?\n"
read appname
echo "{apps:[{name:\"${appname}\",script:\"./cms/bin/www\",watch:false}]}" > process.json

If you need to process more than just a simple line, I second @chepner's suggestion to use a JSON tool such as jq.

Your -bash: process.json: Permission denied comes from the fact you cannot write to the process.json file. If the file does not exist, check that your user has write permissions on the directory. If it exists, check that your user has write permissions on the file.

Is there a tutorial for this? – Noel Harris Mar 03 '21 at 11:07 — Noel Harris, Mar 03 '21 at 11:07
@NoelHarris for what exactly? jq, bash, quoting in bash? – Aaron Mar 03 '21 at 12:27 — Aaron, Mar 03 '21 at 12:27

How to write JSON file using Bash?

2 Answers2