bug#14752: [PATCH] sort: print warning when fork() failed for --compress-program

[Paul Eggert]

Pádraig Brady wrote:
> Anything where you need to interact with the sub process like setting up files
> to communicate etc. is going to have portability issues. Even using execvp()
> is problematic I understand.

As long as the child doesn't touch parent memory that the parent needs, 
it should be OK.  There is a memory leak in execvp in old glibc 
versions, but I expect that isn't something we need to worry about.

Last time I checked, vfork was significantly faster than fork when the 
parent process has a lot of memory, and was still worth using for its 
performance advantages.