closefrom.3bsd man page

library “libbsd”

#include <unistd.h> (See libbsd(7) for include usage.)
void
closefrom(int lowfd);

The closefrom() system call deletes all open file descriptors greater than or equal to lowfd from the per-process object reference table. Any errors encountered while closing file descriptors are ignored.

close(2)

The closefrom() function first appeared in FreeBSD 8.0.