What I have learned is that
fix is called with a data frame, it calls
utils:::edit.data.frame, which will use the default edit on Unix when the GUI is unknown (it is "RStudio" in the case of rstudio.cloud and RStudio Server) or if the DISPLAY is not set (it is ":0"):
if (.Platform$OS.type == "unix" && .Platform$GUI != "AQUA")
if (.Platform$GUI == "unknown" || Sys.getenv("DISPLAY") ==
It will then attempt to launch an external R GUI data frame editor:
out <- .External2(C_dataentry, datalist, modes)
Which fails in the case of rstudio.cloud and RStudio Server.
My understanding is that this known, but that editing a data frame directly is not particularly common.
I am going to move this thread over to the RStudio category.