Grab specific line numbers from a file. You give this routine the name of the file and the name of a file that lists the line numbers to be pulled. The lines are written to standard out.

% cat My.File  
08:13:38.0523 -05:47:34.784 2000.0 NGC2548    1
18:03:53.0406 -00:17:52.912 2000.0 NGC6535    2
19:05:09.8351 +01:52:19.241 2000.0 NGC6749    2
19:11:10.3102 +01:01:31.802 2000.0 NGC6760    2
19:16:34.5168 +30:10:43.325 2000.0 NGC6779    2
19:53:42.8806 +18:46:57.485 2000.0 NGC6838    2

% cat lines
2
4 

% % select_file_lines My.File lines 
18:03:53.0406 -00:17:52.912 2000.0 NGC6535    2
19:11:10.3102 +01:01:31.802 2000.0 NGC6760    2

Fianlly, not that there is another routine that does this sort of thing. It is easier for cutting big, contguous lines from a file. You might look into using cut_by_line for this case.