void im_histlin( variable_list )
The format of ( variable_list ) is:
(image_descriptor, format, arg1,
arg2, ...)
where format, arg1, arg2, ... are the same as in printf. If Hist is NULL, then im_histlin(3) makes up a one-line history, of just the file name.
The user should set up format, arg1, arg2, ... in such a way that the added history line corresponds to the command line which creates the same effect with the same arguments. It can be used after calling an im_function. It is simpler to use the function im_updatehist(3) instead.