gfortran: No such file or directory
MacOS上安装R包的时候报错，如下
* installing *source* package ‘vegan’ ...
** 成功将‘vegan’程序包解包并MD5和检查
** using staged installation
** libs
clang -mmacosx-version-min=10.13 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG -I/usr/local/include -fPIC -Wall -g -O2 -c data2hill.c -o data2hill.o
usr/local/opt/gcc/bin/gfortran -fno-optimize-sibling-calls -fPIC -Wall -g -O2 -c decorana.f -o decorana.o
make: usr/local/opt/gcc/bin/gfortran: No such file or directory
make: *** [decorana.o] Error 1
ERROR: compilation failed for package ‘vegan’
* removing ‘/Library/Frameworks/R.framework/Versions/4.0/Resources/library/vegan’
Warning in install.packages :
installation of package ‘vegan’ had non-zero exit status
Try1：重装gcc
检查发现的确没有这个文件，上网搜说是gcc下的文件,重装gcc就可以，于是用homebrew安装gcc，出现了以下报错
在.zshrc里添加这一行export HOMEBREW_NO_INSTALL_CLEANUP=TRUE，重新安装gcc就没有报错了，gfortran -v也能执行成功，说明gfortran安装没问题了
然后回到Rstudio，安装R包，还是报错说找不到gfortran...
Try2：设置R的环境变量
我想，应该是R环境变量的问题，于是上网搜了搜，看到一个解答
https://blog.csdn.net/u012110870/article/details/105066621
Sys.getenv() 查看R目前的所有环境变量，PATH下的路径都没有gfortran
我的gfortran安装在/usr/local/bin下面，所以把/usr/local/bin添加到PATH
old_path = Sys.getenv("PATH")
new_path = paste(old_path, "/usr/local/bin", sep = ":")
Sys.setenv("PATH" = new_path)
然而安装R包还是报同样的错....
Try3：配置~/.R/Makevars
按照网上建议，配置~/.R/Makevars
https://www.cynkra.com/blog/2021-03-16-gfortran-macos/
cat >> ~/.R/Makevars
FC = usr/local/opt/gcc/bin/gfortran
F77 = /usr/local/opt/gcc/bin/gfortran
FLIBS = -L/usr/local/opt/gcc/lib
重启R，install.packages("picante")，同样的报错...
