Change the criterion for builtins to be safe to execute in the same process in optimized command substitution from a blacklist of only cd, . and eval to a whitelist. This avoids clobbering the main shell environment such as by $(exit 4) and $(set -x). The builtins jobid, jobs, times and trap can still show information not available in a child process; this is deliberately permitted. (Changing traps is not.) For some builtins, whether they are safe depends on the arguments passed to them. Some of these are always considered unsafe to keep things simple; this only harms efficiency a little in the rare case they are used alone in a command substitution.
$FreeBSD$ This directory tree contains tools used for the maintenance and testing of FreeBSD. There is no toplevel Makefile structure since these tools are not meant to be built as part of the standard system, though there may be individual Makefiles in some of the subdirs. Please read the README files in the subdirs for further information.