Behave like the GNU tair -r command or tac command

tac.awk

#!/usr/local/bin/gawk -f

BEGIN {
	# Set delimiter as \034, avoid conflict with other characters
	sort_exe = "sort -t \"\034\" -nr"
}

{
	# Pass to the child process
	printf("%d\034%s\n", NR, $0) |& sort_exe;
}

END {
	# Close the input pipe only
	close(sort_exe, "to");

	# Read output of the child process by using getline
	while ((sort_exe |& getline var) > 0) {
		split(var, arr, /\034/);

		print arr[2];
	}
	close(sort_exe);
}