Set env variable inside sudo statement - Linux shell - linux

Question

I need to modify an environment variable inside a sudo statement. The sudo statement includes some instructions.
In the example, I set the environment variable VAR1 with the value "ABC".
Then, in the sudo statement (and only here), I need to change that value to "DEF". But the value did not change after I set the value to "DEF". Echo commands return "ABC" as the value of VAR1.
How can I change/set the value of the variable inside the sudo statement?
Here an example of the code I run:
#!/bin/bash
export VAR1="ABC"
sudo -u <user> -i sh -c "
export VAR1="DEF";
echo $VAR1;
"
echo $VAR1;
Extra info: I tryed the option -E of sudo, to preserve the environment variable at the moment of sudo invocation (source: https://unix.stackexchange.com/questions/337819/how-to-export-variable-for-use-with-sudo/337820), but the result did not change:
#env VAR1="DEF" sudo -u <user> -E -i sh -c " [...]"

Answer 1

Use single quotes to prevent the outer shell from interpolating $VAR1. You need $VAR1 to be passed to the inner shell so it can expand it.
sudo -u <user> -i sh -c '
export VAR1="DEF"
echo "$VAR1"
'
It's also a good idea to quote variable expansions to prevent globbing and splitting mishaps: write "$VAR1" instead of $VAR1.
(The semicolons aren't necessary since you have newlines.)

Answer 2

Try this
export VAR1="ABC"
sudo -u <user> -i sh -c '
export VAR1="DEF"
echo "${VAR1}"
'
echo $VAR1;
as John Kugelman pointed out, you should use ' instead of " to wrap your command to avoid shell vars interpolation. Also, when referencing to VAR inside the command, use "${}" instead of $, this is what did the trick for me