I would tail /var/log/messages
and plug then in one at a time
Code:
tail -f /var/log/messages
and see if they show up as /dev/video0 /dev/video1 /dev/video2
then you could use streamer and open 3 Terminals
Code:
streamer -q -c /dev/video0 -f rgb24 -r 3 -t 00:30:00 -o /home/jhs/outfile1.avi
streamer -q -c /dev/video1 -f rgb24 -r 3 -t 00:30:00 -o /home/jhs/outfile2.avi
streamer -q -c /dev/video2 -f rgb24 -r 3 -t 00:30:00 -o /home/jhs/outfile3.avi
http://tldp.org/HOWTO/html_single/Webcam-HOWTO/#COMMAND
What kind of webcam post lsusb.