How to safely pipe output to tee?

[Steven W. Orr]

I want to compute a command string which will end up in foo.

Then I want to run that command and cause stdout and stderr to be piped to tee 
for safe keeping while it also goes to the screen.

After the command finishes, I need tee to exit.

It sounds easy, but it's not.

eval "$foo" 2>&1 | tee filename

will cause a hang. Why? Because what $foo does is to start lots of child 
processes and services which do not end. I just want to proceed to the next 
command as soon as $foo completes.

I have the Kudge O The Day currently running, but I'd love to see something 
better. My current setup is this:

mkfifo fifoname
tee filename < fifoname &
teepid=$!
eval "$foo" > fifoname 2>&1
kill $teepid
rm fifoname

And also, BTW, I do need the exit status of the executed command.

Anyone have a better idea?

TIA

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