closefrom.3bsd man page
closefrom — delete open file descriptors library “libbsd” #include < The close(2) The
unistd.h> (See libbsd(7) for include usage.)
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.
closefrom() function first appeared in FreeBSD 8.0.