Applying snapshot diff.gz files - How?

[SHwareSyst at aol dot com]

Hello,

  I'm a relative newcomer to using UNIX based tools, e.g. diff and patch, so 
I was wondering what the bash command line is for applying a diff file from 
the gdb snapshots?? Assume week.tar.bz has been untbz'ed to /src/week/ and 
the diff file week-nextweek.diff.bz has been unpacked there also 
(/src/week/week-nextweek.diff). I'd like to get, effectively, the same files 
as unpacking nextweek.tar.bz over /src/week/.

Thanks in advance,
Mark