program readsac

	parameter(max=400000)
	character nin*100, cmd*100
	real*4 x(max)

	nin='/home/sgao/demo/04_sac/st05.sac'

	open(9,file='filter.mac')

	write(9,91) nin
91	format('read ', a50,/
     &          'rtrend',/
     &          'bp c 0.01 0.1 npoles 4 passes 2',/
     &          'write st05f.sac',/
     &          'quit')
	close(9)

	cmd='sac filter.mac'
	call system(cmd)

	print*,'The filtered SAC file is st05f.sac'

	end