Install_PowerShell_MacOS.sh

#!/bin/bash
############################################################################
# Uninstall / re-install PowerShell on Mac
# per https://github.com/PowerShell/PowerShell/blob/master/docs/installation/macos.md as of 2/18/18
#
# Steps performed by this script, in order:
# * Try to uninstall PowerShell via Homebrew
# * Delete (rm) known PowerShell directories, in case PowerShell was/had been installed via pkg
# * Delete (rm) known PowerShell directories, in case PowerShell was/had been installed via binary
# * Try to re-install PowerShell via Homebrew, after ensuring that Homebrew is updated
############################################################################

# Set UNINSTALL="TRUE" for force deletion of any existing PowerShell directories
UNINSTALL='FALSE'
#PWSHMACURL='https://github.com/PowerShell/PowerShell/releases/download/v6.0.1/powershell-6.0.1-osx-x64.tar.gz'
#PWSHMACVER='6.0.1'

# To install PowerShell Core 6.0+ via Homebrew, local Mac OS must be at least 10.12
req_version='12'

# Detect OS version and confirm OS name
product_name=$(sw_vers -productName)
product_version=$(sw_vers -productVersion)
os_vers=( ${product_version//./ } )
major_version="${os_vers[0]}"
minor_version="${os_vers[1]}"

clear
echo ''
echo '*** Uninstall / re-install PowerShell on Mac ***'
echo "Detected Host OS: $product_name ${major_version}.${minor_version}"
homebrew_version="$(brew --version | grep 'Homebrew >=')"

# To avoid/workaround decimal comparisons, we assume OSX 10.n and only compare minor versions
if [ "${minor_version}" -lt "${req_version}" ]; then
    echo "$product_name ${major_version}.${minor_version} is not supported for package management via Homebrew Cask"
else
    if [ $homebrew_version ]; then
        echo "${homebrew_version}"
        echo 'Try to uninstall PowerShell via Homebrew'
        brew cask uninstall powershell
    else
        echo 'Homebrew not found.'
    fi
echo '*** Install PowerShell Core on macOS (via Homebrew) ***'
echo ''
echo "Detected Host OS: $product_name ${major_version}.${minor_version}"
homebrew_version="$(brew --version | grep -o "\d\.\d\.\d")"

# To avoid/workaround decimal comparisons, we assume OSX 10.n and only compare minor versions
if [ "${minor_version}" -lt "${req_version}" ]; then
    echo " *** Warning: $product_name ${major_version}.${minor_version} not supported for PowerShell package management via Homebrew Cask ***"
fi
echo ''
sleep 2

if [ $UNINSTALL = "TRUE" ]; then
    echo "UNINSTALL: $UNINSTALL"
    echo 'Delete known PowerShell directories'
    sudo rm -rf /usr/local/microsoft /Applications/PowerShell.app
    sleep 1
    sudo rm -f /usr/local/bin/pwsh /usr/local/share/man/man1/pwsh.1.gz
    sleep 1
    sudo pkgutil --forget com.microsoft.powershell
    sleep 1

    sudo rm -rf /usr/local/microsoft
    sleep 1
    sudo rm -f /usr/local/bin/pwsh
else
    echo "UNINSTALL: $UNINSTALL"
fi

if [ $homebrew_version ]; then
    echo 'Try to re-install PowerShell via Homebrew'
    echo 'brew update'
    brew update
    echo ''
    echo 'brew tap caskroom/cask'
    brew tap caskroom/cask
    echo ''
    echo 'brew cask install powershell'
    brew cask install powershell
    echo ''
else
    Installation via Binary Archive
    echo 'Homebrew not found. Proceeding wtih Installation via Binary Archive method'
    echo ''

    Download the powershell '.tar.gz' archive
    temp_file="/tmp/powershell.tar.gz"
    if [ -f "$temp_file" ]
    then
        echo 'powershell.tar.gz downloaded.'
    else
        echo "Downloading powershell.tar.gz from ${PWSHMACURL}."
        curl -L -o /tmp/powershell.tar.gz $PWSHMACURL
    fi

    Create the target folder where powershell will be placed
    target_dir="/usr/local/microsoft/powershell/$PWSHMACVER"
    if ! [ -d "$target_dir" ]; then
       echo "Confirmed folder ${target_dir} exists."
    else
        echo "Creating PowerShell folder ${target_dir}."
        sudo mkdir -p $target_dir
    fi

    Expand powershell to the target folder
    echo 'Expand powershell archive.'
    sudo tar zxf /tmp/powershell.tar.gz -C $target_dir
    echo ''

    Confirm the powershell archive expanded to the target folder
    target_file="$target_dir/pwsh"
    if [ -f "$target_file" ]; then
        echo "Confirmed ${target_file} exists."

        Set execute permissions
        echo 'Set execute permissions'
        sudo chmod +x "${target_file}"
        echo ''

        Create the symbolic link that points to pwsh
        echo 'Creating symbolic link for pwsh.'
        sudo ln -s $target_file /usr/local/bin/pwsh
    else
        echo "*** WARNING! Something didn't go as expected with expanding the archive. ***"
    fi
fi

echo '*** Done! : Now, run $ pwsh to confirm Powershell is installed. ***'

if [ "${minor_version}" -ge "${req_version}" ]; then
    echo 'To update PowerShell via Homebrew, run:'
    echo '     brew update'
    echo '     brew cask upgrade powershell'
    echo ''
fi