问题
What should I write on ${PATH}?
First, I thought it was the directory where the script I was working on.
Second I thought it was the directory where the make or something is.
But both were wrong.
回答1:
${PATH} is the value of the path variable already present on your computer.
PATH="${RTOOLS40_HOME}\usr\bin;${PATH}" is adding ${RTOOLS40_HOME}\usr\bin to the existing path so that RTOOLS can be found when needed.
If RTOOLS installation went correctly, RTOOLS40_HOME environment variable should have automatically been set up to the directory where RTOOLS is installed.
来源：https://stackoverflow.com/questions/62241983/i-dont-know-what-rtools-path-should-be