What does -S mean in gksu -- -S mount …?

So, I have a script that uses -S mount nfs -o proto=tcp,port=2049 … etc. to mount a location from another Linux computer. What does -S mean? It seems to work just fine with or without it (it doesn't work if I do such as gksu -- -S mount … etc. to launch it without a terminal emulator). I'm curious if I actually need -S for some reason, or if I can drop it to make gksu -- work, without consequences. Here's the script I wrote, for reference, with the IP address and paths changed to protect the paranoid: #!/bin/bash if mountpoint -q /home/myLaptop/myDesktop then notify-send -t 3000 "Warning" "It is already mounted." else gksu -- -S mount -t nfs -o proto=tcp,port=2049 192.168.0.x:/home/myLaptop /home/myLaptop/myDesktop if mountpoint -q /home/myLaptop/myDesktop then notify-send -t 3000 "Alert" "Mounted." else notify-send -t 3000 "Alert" "Mount failed." fi fi