R_windows_pipe error_missed.txt

> winCmd <- 'R -q -e "11+1; 1+undef_var; 12+2"'
> pp <- pipe(winCmd, open='r')
> readLines(pp)  # does not return any error message and freezes
[1] "> 11+1; 1+undef_var; 12+2" "[1] 12"                   
> close(pp)

> winCmd <- 'R -q -e "11+1; 1+undef_var; 12+2" 2>&1'
> pp <- pipe(winCmd, open='r')
> readLines(pp)  # works fine
[1] "> 11+1; 1+undef_var; 12+2"           "[1] 12"                             
[3] "Error: object 'undef_var' not found" "Execution halted"                   
> close(pp)

# the reason is pipe does not read stderr stream
# https://blogs.msdn.microsoft.com/ejarvi/2005/01/28/redirecting-stderr-to-stdout-on-the-command-line/