I am attempting to adjust brightness via '/proc/acpi/ibm/brightness',
but I get permission denied if I do it via sudo -- I have to su to root
in order to do the adjustments. Log at [1].
[1]
bryans@esterhazy:~$ sudo echo up > /proc/acpi/ibm/brightness
bash: /proc/acpi/ibm/brightness: Permission denied
bryans@esterhazy:~$ su
Password:
esterhazy:/home/bryans# echo up > /proc/acpi/ibm/brightness
/* Display brightness increases */
[end 1]
I am in my /etc/sudoers file with all permissions. My /etc/sudoers file,
with comments stripped, is at [2].
[2]
Defaults env_reset
root ALL=(ALL) ALL
bryans ALL=(ALL) ALL
[end 2]
My sudoers seems alright as I can execute other privileged commands with
no difficulty, just not mess around with the files in /proc (those few
I've tried)
I don't think it _can_ be a permissions issue, as by my understanding,
absolutely no permission checks are applied to root by userspace --
though correct me if I'm wrong.
I tried to "sudo echo h > /proc/sysrq-trigger", and again was denied.
This led me to look in "$linux/kernel/sysrq.c", but I found nothing
useful in determining why I can't do this using sudo.
I'm left to several possibilities:
1. I'm misunderstanding some documentation somewhere (PEBKAC)
2. sudo cannot allow me to do this, possibly due to restrictions
elsewhere in the kernel [3]
3. I'm able to do this, but I'm just not looking in the right place for
how to enable it
[3] Highly unlikely, by my knowledge.
--
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