ESP32 documentaiont for "time.h" I am working from the example sketch in that installed with the ESP32 Dev Module into the Arduino IDE.  It includes &lt;WiFi.h&gt; and "time.h".  I have a number of questions about how to use the clock that is set up with configTime using NTP. I am trying to find the documentation, but I'm having difficulty identifying exactly who is providing me the "time.h" header file, and of course, there are a lot of different time.h header files out there so googling is difficult.

Where can I find the documentation for this particular header?



Example questions:


Can the time be set manually without a WiFi connection?
Can the timezone be changed without connecting to NTP again?
Can I get the time as a Unix Time Stamp?  (Yes)
Can I arrange for a function callback at a certain time? (I'm aware I can use the timer library for this but I'm hoping for something like a callback at 4:20p every Saturday)
time.h is provided by the compiler (more specifically the C library in use in the compiler).

I believe the xtensa-esp32 compiler uses newlib as the C library. If that is the case, the documentation is here: https://sourceware.org/newlib/libc.html#Timefns