[SOLVED] Startup/Permanent permission change

Johnny_Metal · 05-16-2016, 12:37 PM

Hello everyone,

This file

Quote:

/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0/brightness

is owned by root. I can change the permissions or the owner through the use of chmod or chown commands, but it happens that the changes aren't permanent, and every time I reboot my machine the permissions default to how they were before.

I need to either change the permission for this file permanently or create a script that automatically changes the file permissions at every session startup. I am using the Openbox Window Manager, so i know where the autostart file is.

Any ideas?

HMW · 05-16-2016, 01:25 PM

Instead of doing that, why not use visudo for this. Something like:

Code:

Johnny_Metal ALL=NOPASSWD: /path/to/your/program /sys/class/backlight/acpi_video0/brightness

There is a reason those permissions are what they are I presume. I personally wouldn't mess around with them.

Best regards,
HMW

Edit: For instance, I found it annoying to type the password every time I use the wifi-menu on my Arch Linux machine, so I added this at the END of my visudo configuration:

Code:

## Allow group sudo to run wifi-menu without password
%sudo   ALL=(ALL) NOPASSWD: /usr/bin/wifi-menu

Johnny_Metal · 05-16-2016, 04:16 PM

I've tried out what you told me, but the syntax doesn't work in that way.

From what i've understood, i can post the path to a certain executable. However, my programs aren't allowed to make their changes. I tried adding the following lines for that effect

Code:

jr ALL=NOPASSWD: /home/jr/Brightness_Settings/bup.out
jr ALL=NOPASSWD: /home/jr/Brightness_Settings/bdown.out

It's funny though, because if I simply run them from a terminal window with the sudo command, they work!

I also tried using the scripts you suggested. They work absolutely fine from a terminal, no need for sudo command. Here's the contents i've added to the sudoers and one of the scripts (the other simply differs because it has a - instead of a +)

Code:

jr ALL=NOPASSWD: /home/jr/Brightness_Settings/brightness_up.sh
jr ALL=NOPASSWD: /home/jr/Brightness_Settings/brightness_down.sh

Code:

currentValue=$(cat /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0/brightness)
sudo tee /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0/brightness <<< $((currentValue+2))

However, after adding the path of the scripts to the rc.xml file and reconfiguring OpenBox, it still doesn't work! Here's what the keybinds look like:

Quote:

<keybind key="C-Up">
<action name="Execute">
<command>/home/jr/Brightness_Settings/brightness_up.sh</command>
</action>
</keybind>
<keybind key="C-Down">
<action name="Execute">
<command>/home/jr/Brightness_Settings/brightness_down.sh</command>
</action>
</keybind>

Really appreciated for your help.

EDIT
It ocurred to me that it might somehow be necessary to edit the permissions of the rc.xml file itself... is it possible?

EDIT
Found it out: just need to write the keybinds, whether for the scripts or the my programs together with the sudo command. Together with the permissions, they work just fine.

Thanks a lot for your hep throughout the day!

HMW · 05-17-2016, 01:56 AM

Quote:

Originally Posted by Johnny_Metal

EDIT
Found it out: just need to write the keybinds, whether for the scripts or the my programs together with the sudo command. Together with the permissions, they work just fine.

Thanks a lot for your hep throughout the day!

Awesome. Good work buddy! I took the liberty of highlighting your quote above so that others can find the solution easier.

Best regards,
HMW