The $VAR gotcha: why your command sees an empty value

bash
npx getmyenv run -- psql $DATABASE_URL

The context has DATABASE_URL, but psql gets no URL. If your shell already had a DATABASE_URL, it gets that old value instead.

Your shell expands $DATABASE_URL while it reads the line, before run starts. run sets the variable for the command, but the argument was already replaced. An unset variable disappears from the command, so psql receives no argument at all.

The same thing happens without getmyenv:

bash
unset FOO
FOO=x echo "[$FOO]"            # prints []
FOO=x sh -c 'echo "[$FOO]"'    # prints [x]

In the second line, the single quotes keep your shell away from $FOO. The inner sh starts with FOO set, and expands it then.

bash
npx getmyenv run -- sh -c 'psql "$DATABASE_URL"'

Single quotes pass the text to run as it is. The inner sh starts inside run, with the context's values, and expands $DATABASE_URL there. Keep the double quotes inside, so a value with spaces stays one argument.

When the program reads the variable itself, you need no $ at all. Your own code, and Prisma or drizzle-kit configs that use DATABASE_URL, read it from the environment.

powershell
npx getmyenv run -- powershell -NoProfile -Command 'psql $env:DATABASE_URL'

PowerShell expands $env:DATABASE_URL in your line the same way. In single quotes it passes the text as it is, and the inner PowerShell expands it inside run. With PowerShell 7 installed, pwsh works as the inner shell too.

In cmd.exe, %DATABASE_URL% also expands before run starts. Use the PowerShell line above.

bash
npx getmyenv run --explain
npx getmyenv run -- node -e "console.log(Boolean(process.env.DATABASE_URL))"

npx getmyenv run --explain lists every name and where it comes from. Never values. The second line prints true when the command has the variable, without printing the value. It works the same in bash, zsh and PowerShell.