Reduce Brightness from command line on KaliLinux

Reduce Brightness from command line on KaliLinux:

1. Go to the console and download the following package:

cd /root/Desktop 
wget http://ftp.de.debian.org/debian/pool/main/x/xcalib/xcalib_0.8.dfsg1-2_amd64.deb 
sudo dpkg -i xcalib_0.8.dfsg1-2_amd64.deb

2. Then enter the following command:

xcalib -co 40 -a

//END

3. To reset

xcalib -c

//END

Done.