How Install GDebi package installer on Ubuntu 18.04

We can install deb package in Ubuntu using gdebi package manager and It is the most easiest and efficient way to install deb files manually. Gdebi also better at handling dependency packages than apt.

The gdebi command line tool for Ubuntu 18.04 provides by the gdebi-core package. Here are the steps to install gdebi on Ubuntu 18.04:

Activate the universe repository:
```
sudo add-apt-repository universe
```
Update the package list:
```
sudo apt-get update
```
Install gdebi-core:
```
sudo apt-get install gdebi-core
```

Note that, on the Ubuntu desktop, you need to install the gdebi package if you want GDebi GUI.

sudo apt-get install gdebi

Installing deb files with GDebi Package Installer

To install a deb package from the command line, execute the gdebi command followed by the name of the deb file:

sudo gdebi iftop_1.0~pre4-4_amd64.deb

You need to provide the full path to the .deb package if the deb file is not in the current working directory.

sudo gdebi /root/iftop_1.0~pre4-4_amd64.deb

On the Ubuntu desktop, right click on the deb file and select Open With Other Application > GDebi Package Installer.

Gdebi package installer will identify if any dependent package is also required before installation.