Install Fedora 33 in chroot on Ubuntu 19.10. Installs Cygwin GCC in the Fedora 33 chroot and tests if it works

installCygwinFedora.sh

#!/bin/bash
set -xue

# Script to install Fedora 33 in a chroot on Ubuntu
# And then in turn install cygwin64-gcc in that chroot
# Finally we test we can compile a .exe with Cygwin
#
# Run this as root
#
# Works on Ubuntu 19.10

# Configuration
fedoraver=33
chroot=/fedora${fedoraver}
rpminst=/tmp/rpminst
server=https://download.fedoraproject.org
serverpath=pub/fedora/linux/releases/${fedoraver}/Everything/x86_64/os/Packages/f
serverfile=fedora-repos-${fedoraver}-1.noarch.rpm

# Install yum and yumdownloader
apt install -y yum yum-utils

# Create our chroot
mkdir -p $chroot

# Download and install the fedora-repos package
wget $server/$serverpath/$serverfile
rpm -i --nodeps --force --root=$chroot $serverfile

# Ubuntu's RPM is too old for python-pip-wheel package
# So says YUM. But it works anyway if you do it manually
mkdir -p ${rpminst}
yumdownloader --installroot=$chroot --releasever=${fedoraver} --destdir=${rpminst} python-pip-wheel
rpm -i --nodeps --force --root=$chroot ${rpminst}/*.rpm

# Install DNF and core plugins
yum --installroot=$chroot --releasever=${fedoraver} install -y --nogpgcheck dnf dnf-plugins-core

# Ensure we can resolve DNS
rm -f $chroot/etc/resolv.conf
cp /etc/resolv.conf $chroot/etc

# Enable cygwin DNF repository
chroot $chroot dnf --releasever ${fedoraver} copr enable -y yselkowitz/cygwin

# Install cygwin64-gcc
chroot $chroot dnf --releasever ${fedoraver} install --nogpgcheck -y cygwin64-gcc

# Create test.c
echo $'#include<stdio.h>\nint main(int argc,char*argv){printf("Hello World!\\n");return 0;}' > $chroot/test.c

# Compile test.c
chroot $chroot x86_64-pc-cygwin-gcc -o test.exe test.c