All, I wrote a small Qt app to adjust the display backlight on my laptop: https://paste.opensuse.org/pastes/a67b89db433f It will be a systray app like kmix. As part of the program I write to /sys/class/backlight/ACPI_video0/brightness which is owned by root with 0644 permissions. I have a bash script that does it, but simply using sudo is enough, but how to do the same thing in Qt? I guess I could wrap the write in a system() call using sudo -- but is there a better way to do this? I'd rather not make the executable setuid-root, or something wonky like that. Is there a way to configure the /sys/class/backlight/... file to be owned by the video or wheel group and make users a member of that group? Maybe a new backlight group? If I run it as root, all is well, but if I run as me, it fails, e.g. root: # ./nvidia-bl-qt3 setting backlight: 5 setting backlight: 4 setting backlight: 3 setting backlight: 2 setting backlight: 1 setting backlight: 2 setting backlight: 3 setting backlight: 4 setting backlight: 5 setting backlight: 6 setting backlight: 7 setting backlight: 8 setting backlight: 9 setting backlight: 10 me: $ ./nvidia-bl-qt3 setting backlight: 8 error: file open failed '/sys/class/backlight/acpi_video0/brightness' setting backlight: 9 error: file open failed '/sys/class/backlight/acpi_video0/brightness' setting backlight: 10 error: file open failed '/sys/class/backlight/acpi_video0/brightness' setting backlight: 11 error: file open failed '/sys/class/backlight/acpi_video0/brightness' setting backlight: 12 error: file open failed '/sys/class/backlight/acpi_video0/brightness' setting backlight: 11 error: file open failed '/sys/class/backlight/acpi_video0/brightness' setting backlight: 10 error: file open failed '/sys/class/backlight/acpi_video0/brightness' This is Qt3 (as you could guess from the name), but if you have a way in the current Qt(5/6), I'll dig backwards and find out what the prior equivalent was. Or I could just rewrite in Qt5. === I can't susepaste from TW with my nick and key from 15.4? === Also, why can't I susepaste from TW with my key anymore? I can do it anonymous, but if I pass my nick (-n) and key (-k) copied from 15.4 it always fails? -- David C. Rankin, J.D.,P.E.