Linux Programmer's Manual
NAME
epoll_create, epoll_create1 - open an epoll file descriptor
...
SYNOPSIS
#include <sys/epoll.h>
int epoll_create1(int flags);
...
epoll_create1()
If flags is 0, then, other than the fact that the obsolete
size argument is dropped, epoll_create1() is the same as
epoll_create(). The following value can be included in flags
to obtain different behavior:
EPOLL_CLOEXEC
Set the close-on-exec (FD_CLOEXEC) flag on the new file
descriptor. See the description of the O_CLOEXEC flag in
open(2) for reasons why this may be useful.
https://man7.org/linux/man-pages/man7/epoll.7.html