esetleg szignalozas?
COMMAND1
COMMAND2
COMMAND3
parent=$$
trap 'exit 1' SIGUSR1
(
IFS=:
PATH=/bin
unset TERMINFO
set -C
shift 5
COMMAND4
COMMAND5
if [ ... ] ; then kill -USR1 $parent ; fi
...
)
# The parent shell has not been affected, and the environment is preserved.
COMMAND6
COMMAND7