This is a libusb-1.0 based user space utility to grab the device connected to a IOGEAR GUB211 auto sharing usb switch in Linux. The device shows up with VID=0x2101, PID=0x0231. Since that vendor id belongs to actionstar, I would expect this program to also work with ActionStar's SW-221A and SW-241A, but I haven't tested it. Monoprice's "USB 2.0 2 to 1 Auto Printer Sharing Switch" with product id 5151 has also been tested and works.
This will either need to run as root (you could make it suid) or you will need to use udev rules to set the permissions. The included udev rules allow access to all users, but can be modified (examples included) to allow only a specific user or group.
Compile with:
gcc -Wall -O2 gub211.c -lusb-1.0 -o gub211
then copy the gub211 binary. Copy the 99-gub211.rules to /etc/udev/rules.d and edit if desired.
List devices: gub211 list
Switch to the first device found: gub211 or gub211 first
Switch to the only device: gub211 only
Switch to specific device: gub211 PATH