[prog] gdb debug file input, Linux, C

[ed orphan]

This is a Linux C question.
Is there a way to observe the contents of
a file as it is being created? For example,
in gdb, I have tried to see weather the information
is being entered into a file correctly during 
file creation by indexing the file pointer,
FILE * fp;
   ....... other code, etc ....
   fwrite( nodepointer->structure_name.data_object, 
             sizeof(char), no_of_data_items,  fp );
After this statement I tried to see what was written
into the file
gdb> fp[0]@10
   I get all kinds of stuff on the screen, none of
which helps.
   Do I have to wait until after the file has been
 close(fp);  before I can see what's in it?
 Or is there a method using the gdb debug that
allows me to see how the file is being filled?