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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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How System Requests Work and How to Add Your Own SysReq (snee.la)

submitted 3 weeks ago by [email protected] to c/[email protected]

3 comments fedilink hide all child comments

I needed to add a custom System Request (Sys Req or SysRq) to a linux kernel some time ago. While doing so, I dug deep into how it works and I thought I’d make a quick post about it. Here is a good SuperUser answer about what a SysRq is. You may also know about SysRq via REISUB. This post has three parts: how to raise a SysRq, how SysRq works (looking into kernel code), and how to add your own SysRq.

Disclaimer: This is my website.

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[–] [email protected] 8 points 2 weeks ago (2 children)

Amazing. I've been 'staring' at the sys rq key for 20 years with Linux and many years before with Win/Dos, and never really knew how it worked, for what, or if it was still used for anything - even then.

Apparently (from light search) sysreq was mostly used in the old days to halt current job and enter a systems menu.

Anyway, thanks for fixing a long-standing knowledge gap :-)

[–] [email protected] 5 points 2 weeks ago* (last edited 2 weeks ago)

I'm glad you appreciate it! It's always fun digging into kernel internals and learning new things :D

I'm also open to criticism about the writing if you have any.

[–] [email protected] 3 points 2 weeks ago

No one knows what SysRq was meant for.