curl - How do i download a file from a download link using R -

i have script downloads file download link uses single signon (sso) infrastructure. @ moment i'm using batch script curl download it. how can make equalivent in r download file

curl negotiate -u user:pass -l --insecure -o downloadfilename.xml "https://server/servlet?param1=value1" 

as @tospig suggested use system() so:

system("curl negotiate -u user:pass -l --insecure -o downloadfilename.xml \"https://server/servlet?param1=value1\"")