creating .rpm files for special installations

[g]

greetings.

on firefox tsl, a user of ubuntu needs to run a lan system wide installation
of an extension to firefox.

a reply was to create a .deb package and put in a local repository, add
local repo to all clients repo list.

to add an extension to firefox, appending to some config files is required.

not recalling all abilities of rpm, my question is, can rpm/yum append to
existing files?



tia.
-- 

peace out.

tc.hago,

g
.

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