When I install Haskell/GHC+cabal via sudo apt-get I installed cabal version 1.16. This is obviously not the most up to date version. How would I go about upgrade to at least version 1.18? I tried doing sudo apt-get update and sudo apt-get upgrade.
Edit:
Also when I run cabal install cabal-install it appears to "install" version 1.20 but when I run cabal -V it says cabal 1.16.0
Fixed it by adding the following line to my ~/.profile: export PATH=$(HOME)/.cabal/bin:$PATH
来源：https://stackoverflow.com/questions/25902613/upgrade-cabal-on-ubuntu-14-04