There are two ways to install SExtractor on Ubuntu: from source or binary. I am going to introduce the easier way(i.e. installation from binary) in this page...
Download from http://www.astromatic.net/
when you follow the instruction in user's manual, like
rpm -U sextractor-2.19.5-1.x86_64.rpm
you will get some error
rpm: RPM should not be used directly install RPM packages, use Alien instead!
so let us install Alien first
Install Alien and all dependencies it needs
sudo apt-get install alien dpkg-dev debhelper build-essential
now, you have Alien on your system
Convert a package from rpm to debian format using Alien
sudo alien sextractor-2.19.5-1.x86_64.rpm
then you will get another file with suffix '.deb' under the same directionary, install '.deb' file
sudo dpkg -i sextractor_2.19.5-2_amd64.deb
Now, you can type command: sex(or sextractor or source-extractor)
Screenshot from 2021-04-04 01-04-10.png
