Could you execute this in the RStudio console: Sys.getlocale()
It is getting details of aspects of the locale for this R process which is running inside your RStudio.
Do you have more than one R instances locally installed?
RStudio does not read this file during launch. You can see how R's own GUI uses this file during launch:
In theory, ensuring that the LANGUAGE=en environment variable is set should ensure R uses English messages for output, but I have not been able to verify that this is the case.
I use windows 10
My locale set on my computer is Chinese
I think may be modify the charset to utf-8 is better
So how can I change this setting into utf-8 ?
That probably explains why RStudio is using simplified chines signs: It takes the settings of your OS (and this is simplified chinese). Sys.getenv() gives you a list of all the environment variables that are set, Sys.setenv sets environment variables
Please have a look into the following helpful pages:
?Sys.setlocale in R console returns the R internal help page related to setlocale function