Step 1: Download wacaw from http://webcam-tools.sourceforge.net/
Step 2: Get the list of available devices with ./wacaw -L. Note the device
and input number you want to use.
Step 3: save the script below as timelapse.sh and run it!
#!/bin/bash
interval=${1:-30}
echo "Starting to take pictures every ${interval} seconds."
while true
do
prefix=$(date +%Y-%m-%d:%H:%M:%S)
# allow 10 frames for the camera to adjust brightness
# use appropriate device/input based on Step 2 above
./wacaw --png -x 1280 -y 720 -n 10 -d 3 -i 0 img-${prefix}
echo "Saved img-${prefix}.png"
sleep ${interval}
done