系统：linux/ubuntu
权限：root权限执行
参考网址：Ubuntu Packages For R - Full Instructions (r-project.org)
How to update R 3.x to the new R 4.x in Linux Ubuntu | by Henrique Gomide, Ph.D. | Medium
（1）查看R安装源版本
看到网上大部分教程都是直接apt install r-base
这里需要注意apt r源版本, apt 安源源在配置文件：/etc/apt/sources.list中，可以定义添加
查看R安源源版本，代码如下： #执行其一即可
apt search r-base |grep "^r-base"
apt policy r-base
r-base:
Installed:(none)
Candidate: 3.6.3-1bionic
Version table:
3.6.3-1bionic 500
500 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/ Packages
500 http://cran.rstudio.com/bin/linux/ubuntu bionic-cran35/ Packages
3.6.2-1bionic 500
500 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/ Packages
500 http://cran.rstudio.com/bin/linux/ubuntu bionic-cran35/ Packages
3.6.1-3bionic 500
500 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/ Packages
500 http://cran.rstudio.com/bin/linux/ubuntu bionic-cran35/ Packages
3.6.1-1bionic 500
500 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/ Packages
500 http://cran.rstudio.com/bin/linux/ubuntu bionic-cran35/ Packages
3.6.0-2bionic 500
500 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/ Packages
500 http://cran.rstudio.com/bin/linux/ubuntu bionic-cran35/ Packages
...................
查看
cat /etc/apt/sources.list
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security multiverse
deb https://cloud.r-project.org/bin/linux/ubuntu/ bionic-cran35/
#deb https://cloud.r-project.org/bin/linux/ubuntu/ bionic-cran40/
deb http://cran.rstudio.com/bin/linux/ubuntu/ bionic-cran35/
根据以上可知道 R安装源库版本为cran35, 注意不同ubuntu版本，对应的代号
ubuntu1~18.04： bionic
Ubuntu 20.04 LTS： focal
（2）升级 apt R安装源或者修改R安装源
方案1：
apt update
apt search r-base |grep "^r-base"
如果已经有目的安装R版本，之后直接执行安装代码
apt install r-base # 建议配合安装rstudio-server ，而非rstudio
方案2：
sudo vi /etc/apt/sources.list #系统文件修改，需要root 权限
注释掉bionic-cran35信息行，添加新的信息源（从官网查找：Ubuntu Packages For R - Full Instructions (r-project.org)）
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security universe
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security multiverse
#deb https://cloud.r-project.org/bin/linux/ubuntu/ bionic-cran35/
deb https://cloud.r-project.org/bin/linux/ubuntu/ bionic-cran40/
deb http://cran.rstudio.com/bin/linux/ubuntu/ bionic-cran40/
#deb http://cran.rstudio.com/bin/linux/ubuntu/ bionic-cran35/
然后apt search r-base |grep "^r-base" 命令查看apt install r-base
有需要的安装R版本之后，执行安装命令
如果存在连结R源库地址失败问题，可能是没有获得安装R源网址权限，可以尝试添加一个权限密钥：
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9
（3）升级R包
升级完成后，打开R，执行以下命令，完成R包的升级
update.packages(ask = FALSE, checkBuilt = TRUE)
