[jkramer/mk-17:~]# <foo.awk

BEGIN {
  for(i = 0; i < 5; i++) {
    "date +%s" | getline sec
    print sec
    system("sleep 1")
  }
}
[jkramer/mk-17:~]# gawk -f foo.awk
1436437135
1436437135
1436437135
1436437135
1436437135