One neat idea recently proposed was to support in all our codebase that can do upsdebugx() (so probably via common.c) some dedicated signals consistently:

• either several signals to set specific debug level numbers in a running process (typically daemon like upsd, driver, upsmon; might be a long-running nut-scanner however e.g. to see if it is stuck on something or just a walk takes long),
• or a couple of signals to dial the verbosity up (any limit?) or down (stop at 0),
• or a single signal to dial 0-1-2-3-4-5(-6-...?)-0 which is a bit less reliable as we did not guarantee that the max verbosity is 5 or 6 across the board (some code had debugs at level 10 or so),
• and/or possibly augment the two dialing options above with a dedicated signal to hush the verbosity to 0 quickly.

The first idea with dedicated signals for each debug level may be problematic as we might have no top limit on verbosity (5? more?) and the amount of SIGUSR's may be limited in different OSes.