I can't verify that the environment variable “SECRET_KEY_BASE” is properly set in Linux

My ruby ​​version is 2.6.6, my mysql version is 8.0.23, my mysql2 version is 0.5.3, my bundler version is 2.2.21, my rails version is 5.0.7.2, and my Xcode version is 12.5.

I use macOS Big Sur(version 11.4) and the text editor "Atom".

I'm planning to release my Rails application with the URL of HEROKU(example. https://[My APP Name].herokuapp.com).

I ran the following command.

$ heroku open

The following error occured.

An unhandled lowlevel error occurred. The application logs may have details.

I set two environment variables as below with this command: $ heroku config:set [ENVIRONMENT VARIABLE NAME].

$ heroku config:set DATABASE_USERNAME=****

$ heroku config:set DATABASE_PASSWORD=****

I ran the following command.

$ heroku config

DATABASE_PASSWORD: ****
DATABASE_URL: postgres://****
DATABASE_USERNAME: ****
HEROKU_POSTGRESQL_AQUA_URL: postgres://****
HEROKU_POSTGRESQL_BLACK_URL: postgres://****
LANG: en_US.UTF-8
RACK_ENV: production
RAILS_ENV: production
RAILS_LOG_TO_STDOUT: enabled
RAILS_SERVE_STATIC_FILES: enabled

I ran the following command to get GENERATED_CODE.

$ RAILS_ENV=production rake secret

GENERATED_CODE

I ran the following command.

$ vi /etc/profile

I set the environment variable SECRET_KEY_BASE as below in Vim editor.

# System-wide .profile for sh(1)

if [ -x /usr/libexec/path_helper ]; then
        eval `/usr/libexec/path_helper -s`
fi

if [ "${BASH-no}" != "no" ]; then
        [ -r /etc/bashrc ] && . /etc/bashrc
fi

$ export SECRET_KEY_BASE=GENERATED_CODE

I saved the above SECRET_KEY_BASE and ended Vim editor with the two below commands.

:w !sudo tee %

:q!

I ran the two following command for verifying that the environment variable SECRET_KEY_BASE is properly set in Linux.

$ printenv | grep SECRET_KEY_BASE

$ echo $SECRET_KEY_BASE

But I can't verify that the environment variable SECRET_KEY_BASE is properly set with either of the above commands.