linux - error: could not find function install

i'm having multiple problems r right want start asking 1 of fundamental questions.

i want install github files r, reason install_github function doesn't seem exist. example, when type:

install_github("devtools")

i get

error: not find function install_github

the install_packages function worked fine. how can solve problem?

to add, want ask whether there way upgrade r, since version 2.15.2 doesn't seem compatible of packages want work with.

i'm using linux version 3.6.11-1 redhat 4.7.2-2 fedora linux 17.0 x86-64.

i checked cran website seemed have unupdated versions of r (if possible) dates way '09. love update myself old version of r. advice on too?

install_github function of devtools package. have install , load devtools before using install_github:

install.packages("devtools") library("devtools") install_github("youruser/yourrepo")

GHI