ack-grep to ack in ubuntu
Solution 1:
You link or copy ack-grep to /usr/local/bin so that it gets prioritary in the PATH:
sudo ln -sf /usr/bin/ack-grep /usr/local/bin/ack
Or, like davey suggested, get rid of ack if you don't need it:
sudo apt-get remove ack
Another solution would involve using dpkg-divert to tell dpkg that you want all packages to have their /usr/bin/ack renamed locally and then link ack-grep to ack in the path.
Solution 2:
In Ubuntu/Debian you can "divert" ack-grep:
sudo dpkg-divert --local --divert /usr/bin/ack --rename --add /usr/bin/ack-grep