Separate variable scope spawning commands under job control

Question

Is is possible in bash - or other sh-derivative shell - to run in the foreground from command-line a list of commands that have their own variable scope (so any values assigned to variables in that scope will not known outside that scope), but also - if spawning a background command - that background command still be a job under the parents shell, i.e. still under the command-line shell's job control? If there are more than 1 way to do this, which way is the most practically short?

I know using parentheses will create new subshell that have its own scope, but any spawned background command will not be under the shell's job control anymore.

Answer 1

In zsh, you can use an anonymous function, but you still need to declare variables as local.

For instance:

$ () { local t; for t in 100 200 300; do sleep $t & done; }
[2] 4186
[3] 4187
[4] 4188
$ jobs
[2]    running    sleep $t
[3]  - running    sleep $t
[4]  + running    sleep $t
$ typeset -p t
typeset: no such variable: t

With any shell with support for local scope in functions, you can use a normal function like:

run() { eval "$@"; }

Then:

run 'local t; for t in 100 200 300; do sleep "$t" & done'