My own environment variables

I have several domains (Users) on a VPS. When I did printenv, I noticed that Hestia has separate environment variables for each user. I couldn’t find where they are stored.

The thing is that I need to use my own environment variables with some users. The question is:
Where or how can I create my own separate variables for each user?

Hestia creates a file hestia.sh in dir /etc/profile.d/hestia.sh and it creates variable HESTIA and adds /usr/local/hestia/bin to PATH. I don’t know if you are seeing any other variables related to Hestia.

$ cat /etc/profile.d/hestia.sh
export HESTIA='/usr/local/hestia'
PATH=$PATH:/usr/local/hestia/bin
export PATH

Will depend on the shell you are using but e.g. for bash you can add those variables to bash startup files, usually ~/.bashrc and/or ~/.bash_profile but it will depend whether you will use the shell interactively or not, more info here:

Yes, and how do I set my own variables? The thing is that I need, for example.
DB_HOST, DB_NAME, DB_PASS, the thing is that I can’t do them globally, since each site that uses databases, the DB_NAME and DB_PASS are different.

Is there a way to do it for each user that needs those variables?

For PHP you can’t as they are unique for each website

@eris It would have to be done with composer, right?

I have other doubts here.
1.- Should I install Composer?
2.- Upload composer.json
3.- Upload composer.lock
4.- Upload the .env file. I don’t know at what level I should upload it, if within public_html or at the same level?