How does a command that runs without sudo edit a file that only root has permission to?

Question

bash

xbackligh stopped working. But if you write the brightness value to /sys/class/backlight/intel_backlight/brightness the brightness of the display changes. I have already tried all the ways to restore its performance, the question is: How did a command that is not run from root write to a file that cannot be edited without superuser rights? (previously xbackligh worked without sudo, and the brightness was changed with the xbacklight -inc 10 / xbacklight -dec 10 commands). I'm interested in writing my own script that will write and read from this file. So far, it only comes to mind to create a group, add yourself and the root there, and give editing rights to the members of the group. But I'm afraid that this would not have a negative impact on security.

Answer 1

suid bit on the executable, but should be used with care.