Shell command - How to run? - json

Question

When I put a command on terminal, it works just fine, but when I put the same command in a .sh script and then run it, it doesn't give any output. What might be the reason for this?
The command:
IFS=$'\t'; while read -r k v; do
export "$k=\"$v\""

Answer 1

This is kind of expected since export sets the environment variable for that particular shell.
Docs -
export command is used to export a variable or function to the
environment of all the child processes running in the current shell.
export -f functionname # exports a function in the current shell. It
exports a variable or function with a value.
So when you create a sh script it runs the specified commands into a different shell which terminates once the script exits.
It works with the sh script too -
data.sh
#!/bin/bash
IFS=$'\t'; while read -r k v; do
export "$k=\"$v\""
echo $HELLO1
echo $SAMPLEKEY
done < <(jq -r '.data | to_entries[] | [(.key|ascii_upcase), .value] | #tsv' data.json)
Output -
$ ./data.sh
"world1"
"world1"
"samplevalue"
Which suggests that your variables are getting exported but for that particular shell env.
In case you want to make them persistent, try putting scripts or exporting them via ~/.bashrc OR ~/.profile.
Once you put them in ~/.bashrc OR ~/.profile, you will find the output something as below -
I used ~/.bash_profile on my MAC OS -
Last login: Thu Jan 25 15:15:42 on ttys006
"world1"
"world1"
"samplevalue"
viveky4d4v#020:~$ echo $SAMPLEKEY
"samplevalue"
viveky4d4v#020:~$ echo $HELLO1
"world1"
viveky4d4v#020:~$
Which clarifies that your env variables will get exported whenever you open a new shell, the logic for this lies in .bashrc (https://unix.stackexchange.com/questions/129143/what-is-the-purpose-of-bashrc-and-how-does-it-work)
Put your script as it is ~/.bashrc at the end -
IFS=$'\t'; while read -r k v; do
export "$k=\"$v\""
echo $HELLO1
echo $SAMPLEKEY
done < <(jq -r '.data | to_entries[] | [(.key|ascii_upcase), .value] | #tsv' data.json)
You need to make sure that data.json stays in user's home directory.

Answer 2

Basically: A child process can't change the environment of it's parent process.
You need to source the script instead of executing it:
source your_script.sh
source runs the script in the current shell which makes it possible to modify the environment.
Alternatively you can create a function in your shell startup files (e.g. ~/.bashrc):
my_function() {
IFS=$'\t'; while read -r k v; do
export "$k=\"$v\""
done < <(jq -r '.data | to_entries[] | [(.key|ascii_upcase), .value] | #tsv' /path/to/data.json)
}
After you've started a new shell you can run
my_function