SDB help

[Richard Silverman]

I am trying to use sdb under System V.  I would like to patch the value of
a global variable.  I have compiled & linked the image with the -g option.
I get the following:

% sdb -w imagefile
No core image
*:variable!1
No process and/or file
* ...

If I oblige it by starting a process running the image, then the command
works, but of course it only sets the variable in memory; I want to patch
the image file.  The manual says that "if a process is running, all addresses
refer to memory; otherwise, they are file offsets" (or something like that).
What's more puzzling is that I made it work once!  But I haven't the foggiest
notion what did it, and it doesn't work now.  Can anyone enlighten me?  Thanks,

                                                Richard Silverman

arpa:	rsilverman at eagle.wesleyan.edu           Computing Center
bitnet:	rsilverman at wesleyan                     Wesleyan University
CIS:	[72727,453]                             Middletown, CT 06457