From mboxrd@z Thu Jan  1 00:00:00 1970
From: edacval@gmail.com (edacval at gmail.com)
Date: Thu, 30 Dec 2010 02:49:29 +0200
Subject: Getting the magic Sysrq key to work (on Ubuntu)
In-Reply-To: <AANLkTimttCD4peJSDnE3FdYKVkzyHOqOH=YctmBug0Jx@mail.gmail.com>
References: <AANLkTimttCD4peJSDnE3FdYKVkzyHOqOH=YctmBug0Jx@mail.gmail.com>
Message-ID: <4D1BD719.8090305@gmail.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hi

> 
> Note that trying to sudo echo a value into /proc/sys/kernel/sysrq doesn't
> work:
> 
> *julie at zeus:/proc/sys/kernel$ cat sysrq
> 0
> julie at zeus:/proc/sys/kernel$ sudo echo "1" > sysrq
> bash: sysrq: Permission denied
> julie at zeus:/proc/sys/kernel$ ls -l sysrq
> -rw-r--r-- 1 root root 0 2010-12-29 19:37 sysrq
> *
> Instead, I have to explicitly log in as root:
> 
> *julie at zeus:/proc/sys/kernel$ cat sysrq
> 0
> julie at zeus:/proc/sys/kernel$ su
> Password:
> root at zeus:/proc/sys/kernel# echo "1" > sysrq
> root at zeus:/proc/sys/kernel# exit
> exit
> julie at zeus:/proc/sys/kernel$ cat sysrq
> 1*
> 
> or sudo a shell:
> 
> *julie at zeus:/proc/sys/kernel$ sudo bash
> [sudo] password for julie:
> root at zeus:/proc/sys/kernel# echo "1" > sysrq
> root at zeus:/proc/sys/kernel# exit
> exit
> julie at zeus:/proc/sys/kernel$ cat sysrq
> 1*
> 
> Which I presume might be counter-intuitive for some Ubuntu users, as AFAICR
> they're not encouraged to create an explicit root account but are expected
> to sudo
> everything instead - in other words they're likely to simply tag 'sudo' in
> front of
> any CL operation that would normally be root-only and expect it to work.
> 
sudo bash -c "echo 1 > /proc/sys/kernel/sysrq"
or
echo "1" |sudo tee /proc/sys/kernel/sysrq