A very simple script for displaying your Wi-Fi's signal strength and link quality using the iwconfig utility (tested on Linux (Ubuntu) only).
python wlansignal.py interface_name
If interface_name is not specified, the default value wlan0 will be used.
---Press CTRL+Z or CTRL+C to stop.---
Link Quality=36/70 Signal level=-74 dBm
Link Quality=52/70 Signal level=-58 dBm
Link Quality=39/70 Signal level=-71 dBm
Link Quality=41/70 Signal level=-69 dBm
Link Quality=38/70 Signal level=-72 dBm
Link Quality=39/70 Signal level=-71 dBm
Link Quality=54/70 Signal level=-56 dBm
Link Quality=37/70 Signal level=-73 dBm
Link Quality=38/70 Signal level=-72 dBm
Link Quality=39/70 Signal level=-71 dBm
Link Quality=37/70 Signal level=-73 dBm
Link Quality=37/70 Signal level=-73 dBm
http://www.calazan.com/how-to-continuously-monitor-your-wi-fis-signal-strength-in-ubuntu/