Is there a way to start a Linux machine automatically?

Question

On Mac machines the user can schedule the machine to power-on automatically, is there anything for Linux that gives us the same ability? I can schedule shut downs whenever I want, it's powering up that I want to do.

Answer 1

Assuming that your hardware supports it, you should be able to set the alarm from within linux by writing to /sys/class/rtc/rtc0/wakealarm or /proc/acpi/alarm. More info here and here, respectively. Note that this facility may become available with a BIOS update.

It may also be possible for this option to be available even if the BIOS interface doesn't allow it to be set. My laptop has a bare-bones BIOS interface, but although I haven't tried to wake it via the alarm, it looks like it's possible. This is based on the fact that one of the /var/log/kern.log* files contains the text RTC can wake from S4, and from the presence of the (empty) pseudo-file /sys/class/rtc/rtc0/wakealarm. More on that at the same page linked to by the above links.

Answer 2

It's not about OS, it's about the hardware.

Some BIOSes have a "wake on RTC alarm" option. Assuming that your bootloader doesn't want for user input forever, your OS shall boot as soon as BIOS powers on the computer at certain time.