Small script that uses iwlist to scan for local ESSIDs. The script can include a list of ESSIDs to exclude from the output, for, i.e. trying to see when a new AP/ESSID appears and can create an archive of all the ESSIDs it's seen. Accordingly, if you leave it running in loop mode, it will record all the ESSIDs it sees coming in and out of range. The original impetus for this script was when I was configuring some embedded devices that acted as APs for initial configuration. Often, they would not appear after carrying out the devices procedures for getting it into AP mode. Having the ability to see when the AP pops up was useful for eliminating some guesswork (and frustrating attempts to get get connected to them).