When you specify the -g option to cc:
$ cc -g test.c
you arrange for the compiler to generate
information about program variables and statements
that will be used by the debugger
dbxtra(CP),
or its Motif/X11 interface-oriented version,
dbXtra(CP).
The information supplied to dbxtra will allow you to
use it to trace function calls,
display the values of variables, and set breakpoints.
See
``dbXtra and dbxtra''
for further information.