bash: variable defining environment variables

Question

In Bash, this work:

FOO=foo BAR=bar a_command

But how to make it works?

ENV="FOO=foo BAR=bar"
$ENV a_command

I got:

FOO=foo: command not found

Answer 1

See if this helps:

  sh -c "$ENV a_command"

Answer 2

This is what the env command is for

env $ENV a_command

Note that the behaviour you see is documented in the manual -- the shell looks for variable assignments before expanding variables.