The O_CLOEXEC flag of open (and FD_CLOEXEC flag of fctl) can help you control which file descriptors will be automatically closed on exec. Otherwise, you have t

The O_CLOEXEC flag of open (and FD_CLOEXEC flag of fctl) can help you control which file descriptors will be automatically closed on exec. Otherwise, you have to manually close the files between a fork and an exec.