Alt+SysRq on a laptop

Question

I have a Lenovo T410, and I would like to use the SysRq key, but whenever I press the Alt+SysRq+letter combination, I keep getting the print screen dialog in linux.

Is there a way around this? I have tried pressing Ctrl+Alt+SysRq+letter as well as Fn+Ctrl+Alt+SysRq+letter but to no avail for any of these. Any information to get around this would be great.

Solution 1

It's not the same for all laptops unfortunately, but the general idea is to consult the manual to figure out the SysRq and then use Alt in addition to that, for example this is Lenovo X1:

Lenovo X1 Carbon user manual mentions SysRq is Fn + S, I managed to trigger SysRq combination using the following sequence:

• Press and hold Fn + Alt + S
• Release both Fn and S
• Press and release the desired key (e.g. h to show the SysRq help)
• Release Alt

Solution 2

I was struggling a bit with the answers given here, so maybe the following additional details might help others like me who have no prior experience with the sysrq key and would like to give it a try:

According to the manual, on my W510 the sysrq key is Fn + PrintScreen. (Googling Thinkpad <your Thinkpad model> manual should get you the manual. Then, search for sysrq in the manual itself.)

Finally, the magic sysrq key combinations can be reached through:

1. Hold down Alt.
2. Hold down Fn and PrintScreen for a moment and then release the two keys again. (They basically act as one key.) Meanwhile, keep holding down Alt.
3. Hit the remaining key of the magic sysrq key combination you would like to use (e.g. h for help or b for reboot).
4. Release Alt.

Side note 1: For ergonomic reasons I had swapped the Fn and Ctrl keys in my Thinkpad's BIOS (as is possible with practically any Thinkpad), so in my case I actually have to hit the left Ctrl key whenever I want to use the Fn key. In case of the sysrq key this is no different!

Side note 2: Whenever the table on Wikipedia says a key combination will "display" certain information, what is meant is that the information is going to be written to the system log, which can be accessed through e.g. $ dmesg or $ less /var/log/syslog. At the same time, if you're logged in on any TTY (Ctrl + Alt + F[1-6]), then the same information will also be displayed there. Similarly, the kernel will respond with a message in the logs if a certain sysrq operation you're trying to use is disabled.

Side note 3: On Ubuntu there's a file /etc/sysctl.d/10-magic-sysrq.conf controlling which magic sysrq key chords are available/enabled and which aren't.

Solution 3

On most laptops (I haven't verified on the T410):

• Press and hold both Fn and Alt.
• Press and hold SysRq.
• Release Fn, and optionally Alt (but keep SysRq down).
• Press the letter or other key.
• Release everything and massage your sore fingers.

This holds for desktops as well: you can release Alt after you're holding SysRq, that way you only need to hold two keys at a time.

Comments

[LatinSuD]

In my HP i do: Alt Fn SysRq (release Fn) (release SysRq) (release Alt)

[Martian2020]

it is just that Fn+S gives you printscreen (Checked on my thinkpad, I guessed they use same, X1 have several gens anyway so it is no one model). Alt+PtScr works too (alt first) as described in en.wikipedia.org/wiki/Magic_SysRq_key.

[Malvineous]

Confirmed, Fn + S does work when combined with Alt as described, but it's far easier to use Alt + PrtSc. The process is the same - hold Alt, press and release PrtSc, then press and release h, then let go of Alt. To confirm you can run dmesg -w in a terminal and then press SysRq + h and you should see help messages come out if it's working.