pro pack,lpack_filename,filelist,verbose=verbose,output_dir=output_dir
  if n_elements(output_dir) gt 0 then pack_filename=output_dir+lpack_filename else pack_filename=lpack_filename
  file_delete,pack_filename,/allow_nonexistent,verbose=verbose

  ;Tar it up
  if (!VERSION.OS_FAMILY eq 'Windows') then begin
     file_delete,pack_filename+'.filelist.txt',verbose=verbose,/allow_nonexistent
     openw,ouf,pack_filename+'.filelist.txt',/get_lun
     for i=0,n_elements(filelist)-1 do printf,ouf,'"'+filelist[i]+'"'
     close,ouf
     free_lun,ouf

     spawn_cmd = !7Z_PATH+'\7za a -r -ttar "'+pack_filename+'" "@'+pack_filename+'.filelist.txt"'

     if keyword_set(verbose) then print, spawn_cmd
     spawn, spawn_cmd,/noshell,result

    ;clean up the file list
    file_delete,pack_filename+'.filelist.txt',verbose=verbose
  endif else begin
     if keyword_set(verbose) then tar_cmd='tar cv ' else tar_cmd='tar c '
     tar_cmd += '-f '+  pack_filename

     for file_index=0, n_elements(filelist)-1 do begin
        if strpos(filelist[file_index],'*') ge 0 then begin
          tar_cmd +=' `find . -name "'+filelist[file_index]+'" | sed "s/^\.\///g"`'
        end else begin
          tar_cmd +=' ' + filelist[file_index]
        end
     endfor
     if keyword_set(verbose) then print, tar_cmd
     spawn, tar_cmd, result
  endelse
  ;show output
  if keyword_set(verbose) then for i=0,n_elements(result)-1 do print,result[i]
end