ProcessInfo systemUptime

[There’s nothing Swift specific here so I’ve moved the thread over to Core OS > Kernel, which is probably the best match.]

The problem here is one of definition. By my count there are three separate concepts entangled here:

• How long has the CPU been running? (A)

• When did the computer boot? (B)

• How much time has expired between then and now? (C)

Which one of these do you want?

ps I believe that

systemUptime

is returning A. As far as I can tell the

uptime

command-line tool is basing its calculation on B. Finally, note that B and C aren’t necessarily in sync because the system clock might have changed.

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—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Hi Eskimo,

thanks for your feedback on that.

What I need is to have the same exact result of the terminal command "uptime". Based on what I see here, (A) which is the output of the API "systemUptime" is giving me back the "awake" time. I think this has clarified my doubt 🙂

Many thanks and have a good day!

Gennaro

What I need is to have the same exact result of the terminal command

uptime

.

uptime

is part of Darwin, so you can just look at the source code. Specifically, check out the

pr_header

routine in w.c. It uses the

CTL_KERN

>

KERN_BOOTTIME

selector to

sysctl

to get the kernel boot time and then does calendar maths from there.

IMPORTANT Personally I wouldn’t replicate this calendar maths because it’s hopelessly naïve. Rather, I’d use

NSCalendar

to calculate this difference, or just go straight to

NSDateComponentsFormatter

to render the difference.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"