Sys.setenv("SNC_LIB" = lib_path_64) fails - r

Question

I'm using the package RSAP to read SAP data.
RSAP loads a SNC (Secure Network Connection) dynamic library and searching for it with the environment variable SNC_LIB.
Depending on the local user system, this might be a 32 or 64 bit library.
I'm setting the environment variable within my R script.
But RSAP still search in the old path.
I try to avoid setting the environment variable outside by application because it's a shiny app which should be used by many users.
It seems that the environment variable is changed only within the RSTUDIO session but not outside.
Initial situation of the environment variables within RStudio console:
> Sys.getenv("SNC_LIB_64")
[1] "C:\\Program Files\\SAP\\FrontEnd\\SecureLogin\\lib\\sapcrypto.dll"
> Sys.getenv("SNC_LIB")
[1] "C:\\Program Files (x86)\\SAP\\FrontEnd\\SecureLogin\\lib\\sapcrypto.dll"
Coding:
# check SNC_LIB path from environment variables
# 32 or 64 bit?
# if 64 bit lib path is set, set the default lib path variable
# SNC_LIB to it
lib_path_64 <- Sys.getenv("SNC_LIB_64")
if (lib_path_64 != "") {
Sys.setenv("SNC_LIB" = lib_path_64)
}
After the code is executed in RStudio debugger:
Browse[2]> Sys.getenv("SNC_LIB")
[1] "C:\\Program Files\\SAP\\FrontEnd\\SecureLogin\\lib\\sapcrypto.dll"
Error thrown by RSAP on loading the library:
[Thr 12160] Wed Jan 03 17:42:57 2018
[Thr 12160] *** ERROR => SncPDLInit()==SNCERR_INIT, Adapter #1 (C:\Program Files (x86)\SAP\FrontEnd\SecureLogin\lib\sapcrypto.dll) not loaded [sncxxdl.c 727]
Old path is used. When I change the path outside before running RStudio it's working.
Question:
Is there a way to set the library path variable SNC_LIB in another way to be sure is globally and not locally changed and RSAP dynamic loading is working well?
Easy way to reproduce is:
Start RStudio
Call Sys.setenv("TEST_VAR" = "good")
Call Sys.getenv("TEST_VAR")
See right result [1] "good"
Close RStudio
Start RStudio again
Call again Sys.getenv("TEST_VAR")
See 'wrong' unexpected result [1] ""

Answer 1

Environment variables set in R affect that process and processes it runs, they don't persist when R quits.
It's not clear what steps you took to lead to your RSAP error, but your "easy code to reproduce" script is acting as expected.
The only way a Sys.setenv() in an R session will affect a subsequent library load is if that load is happening in the R session (e.g. loading an R package that loads the library) or in a process R launches (e.g. running a command using system()).