I have fully updated Ubuntu 16.04.7 LTS amd64 which was configured for RMarkdown/bookdown, LaTeX publishing using the following commands:
sudo apt-get install apt-transport-https
cat <<EOF | sudo tee /etc/apt/sources.list.d/r-cran.list
deb https://cloud.r-project.org/bin/linux/ubuntu xenial/
EOF
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9
sudo apt-get update
sudo apt-get install -y r-base-dev libssl-dev libjpeg62 libgstreamer0.10-0 libgstreamer-plugins-base0.10-0 calibre
sudo apt-get install -y biber texlive-lang-cyrillic fonts-cmu texlive-xetex texlive-fonts-extra texlive-math-extra font-manager ttf-mscorefonts-installer lmodern
sudo apt-get install -y build-essential libcurl4-openssl-dev libxml2-dev libcairo2-dev git
wget https://github.com/jgm/pandoc/releases/download/2.11.4/pandoc-2.11.4-1-amd64.deb -O /tmp/pandoc.deb
sudo apt-get install -y /tmp/pandoc.deb
wget -c https://download1.rstudio.org/desktop/xenial/amd64/rstudio-1.4.1106-amd64.deb -O /tmp/rstudio.deb
sudo apt-get install -y /tmp/rstudio.deb
mkdir -p ~/R/x86_64-pc-linux-gnu-library/3.4
R -e "install.packages(c('bookdown','tikzDevice','xaringan'), repos='http://cran.rstudio.com/', lib='/home/$USER/R/x86_64-pc-linux-gnu-library/3.4')"
This means that its /etc/apt/sources.list /etc/apt/sources.list.d/*.list
contains the following lines:
$ grep ^deb -r /etc/apt/ --include=*.list
/etc/apt/sources.list.d/r-cran.list:deb https://cloud.r-project.org/bin/linux/ubuntu xenial/
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ xenial main restricted
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ xenial-updates main restricted
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ xenial universe
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ xenial-updates universe
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ xenial multiverse
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ xenial-updates multiverse
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu xenial-security main restricted
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu xenial-security universe
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu xenial-security multiverse
and this system has the following set of R packages:
$ dpkg -l | grep "^ii r-"
ii r-base 3.4.4-1xenial0 all GNU R statistical computation and graphics system
ii r-base-core 3.4.4-1xenial0 amd64 GNU R core of statistical computation and graphics system
ii r-base-dev 3.4.4-1xenial0 all GNU R installation of auxiliary GNU R packages
ii r-base-html 3.4.4-1xenial0 all GNU R html docs for statistical computing system functions
ii r-cran-boot 1.3-20-1xenial0 all GNU R package for bootstrapping functions from Davison and Hinkley
ii r-cran-class 7.3-14-2xenial0 amd64 GNU R package for classification
ii r-cran-cluster 2.0.7-1-1xenial0 amd64 GNU R package for cluster analysis by Rousseeuw et al
ii r-cran-codetools 0.2-15-1cran1xenial0 all GNU R package "Code Analysis Tools for R"
ii r-cran-foreign 0.8.70-1xenial0 amd64 GNU R package to read/write data from other stat. systems
ii r-cran-kernsmooth 2.23-15-3xenial0 amd64 GNU R package for kernel smoothing and density estimation
ii r-cran-lattice 0.20-38-1cran1xenial0 amd64 GNU R package "Trellis Graphics for R"
ii r-cran-mass 7.3-50-1xenial0 amd64 GNU R package of Venables and Ripley's MASS
ii r-cran-matrix 1.2-14-1xenial0 amd64 GNU R package of classes for dense and sparse matrices
ii r-cran-mgcv 1.8-28-1cran1xenial0 amd64 GNU R package "Mixed GAM Computation Vehicle with
ii r-cran-nlme 3.1.137-1xenial0 amd64 GNU R package for (non-)linear mixed effects models
ii r-cran-nnet 7.3-12-2xenial0 amd64 GNU R package for feed-forward neural networks
ii r-cran-rpart 4.1-15-1cran1xenial0 amd64 GNU R package "Recursive Partitioning and Regression
ii r-cran-spatial 7.3-11-1xenial0 amd64 GNU R package for spatial statistics
ii r-cran-survival 2.44-1.1-1cran1xenial0 amd64 GNU R package "Survival Analysis"
ii r-doc-html 3.4.4-1xenial0 all GNU R html manuals for statistical computing system
ii r-recommended 3.4.4-1xenial0 all GNU R collection of recommended packages [metapackage]
From previous experience I know that some of R packages are newer than versions from Ubuntu 18.04.6 LTS official repository.
How should I upgrade this Ubuntu 16.04.7 LTS to Ubuntu 18.04.6 LTS correctly in this situation?