The following config will guide you through a process of installing Cran R-3.2.1 on Debian Linux 8 Jessie. First, updated you repository list:
# apt-get udpate
If you have not done so yet install a curl command which you will use to download Cran R-3.2.1 source code:
# apt-get install curl
Next, install all compilation dependencies in order to compile Cran R-3.2.1 source code:
# apt-get build-dep -y r-base
Download Cran R-3.2.1 source gzip tarball and extract its content:
# curl https://cran.r-project.org/src/base/R-3/R-3.2.1.tar.gz | tar xz
Navigate to extracted R-3.2.1 directory:
# cd R-3.2.1
As a last step compile and install Cran R-3.2.1:
./configure; make; make install
Confirm installed Cran-R version:
# R --version
R version 3.2.1 (2015-06-18) -- "World-Famous Astronaut"
Copyright (C) 2015 The R Foundation for Statistical Computing
Platform: x86_64-unknown-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under the terms of the
GNU General Public License versions 2 or 3.
For more information about these matters see
http://www.gnu.org/licenses/.
Run R:
$ R

R version 3.2.1 (2015-06-18) -- "World-Famous Astronaut"
Copyright (C) 2015 The R Foundation for Statistical Computing
Platform: x86_64-unknown-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

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