Comment by zzo38computer

I agree with it, although still the fork is expensive like they mention. There is clone with some flags, although that does not really solve it.

I think one problem is that it is already how it is; making an entirely new operating system (that is not Linux, not GNU, and not POSIX) would solve it, but that is not the case here, so it would need to be done as it is.

One possibility would be a new function that creates a new empty child process, but the parent process specifies what system calls the child process executes, and can stop if specifying that exec or exit is (successfully) called by the child process, or if the parent process gives it the program memory to execute directly instead of using a file (since that use is also useful). The new function can still have some of the clone flags available. (I don't actually know how much better it would work.)

There are other possibilities as well.

The existing methods can also remain available for when they are helpful, but functions such as popen might be changed to use the new method.