Example of how to do freshy RPi3B+ setup for things like FLDIGI and other applications which use Qt libraries.

setupRPi3BPlus.sh

#!/bin/bash
#edit /etc/apt/sources.list and uncomment the source line
sudo sed -i '/#deb-src/s/^#//g' /etc/apt/sources.list
# do a apt update to grab the source package data
# if that fails due to network missing, kills the script
sudo apt update && sudo apt build-dep fldigi
sudo apt install qt5-default qtmultimedia5-dev libqt5serialport5-dev
# libqt5network5-dev
# Edit /etc/dphys-swapfile and change CONF_SWAPSIZE=100
# to CONF_SWAPSIXE=1024 to help compile FLDIGI
# comment out the swapsize = 100 line if not commented already
sudo sed -i '/CONF_SWAPSIZE=100/s/^#*/#/g' /etc/dphys-swapfile
# Add a new line with the proper size for compiling
sudo sed -i '/#CONF_SWAPSIZE=100/ a CONF_SWAPSIZE=1024' /etc/dphys-swapfile
# Run setup to create the new swap file
sudo dphys-swapfile setup
# Turn it off so we can let it resize
sudo dphys-swapfile swapoff
# Turn it back on to use the new size
sudo dphys-swapfile swapon
# Download fldigi
cd ~
mkdir src
cd src
wget http://www.w1hkj.com/archives/Source/fldigi/fldigi-4.1.11.tar.gz
tar xvzf fldigi-4.1.11.tar.gz
cd fldigi-4.1.11
./configure && make -j2
sudo make install
#
# Now remove the swap file completely for production
# and to make the SD card last longer
sudo dphys-swapfile swapoff
sudo dphys-swapfile uninstall
#
echo "Let's try it all out!"
sleep 5 
sudo reboot