请教这个fortran脚本怎么用？据说是把txt文件转化成cst文件 linux下怎么操作 谢谢

下面是.f文件具体内容
parameter(npointp=900000)
real x(900000),y(900000)
integer num(900000),linenum(900000),npl(900000),lnum,nplt,
* lasti,i,j

    open(10, file='coastline.txt') 
    open(11, file='coastline.cst') 

  do i=1,npointp 
     read(10,*,end=100) num(i), y(i), x(i) 
  enddo 

100 continue
npoint=i-2
close(10)
lnum=0
nplt=0
lasti=0
do i=1,npoint

     if(num(i).eq.3) then 
    lnum=lnum+1 
    npl(lnum)=i-lasti 
    lasti=i 
     end if 
  enddo 

  write(11, *) 'COAST' 
write(11,'(I5,f4.1)') lnum,0.0 
  j=1 
  do i=1, npoint 
  print*,i 
      if(num(i).eq.1) then 
    write(11,'(I5,I4)')npl(j),0 
    j=j+1 
  endif 
  write(11,30) x(i),y(i),0.0 
enddo 

30 format(1x,2f20.4,f5.1)

   close(11) 
end