Codesign macOS Installer package

gistfile1.txt

# Automator > Quick Action
# Workflow receives current "files or folders" in "Finder"
# Add "Run Shell Script" action
# Copy script below to "Run Shell Script" window
# Replace <codesigning certificate> at row 28 with your certificate information
# Save quick action as: "Sign Installer package"

# Quick Actions live in: ~/Library/Services

# Receives files and folders
while read -r file; do
    dest_dir="${file%/*}"
    filename="${file##*/}"
    filename="${filename%.*}"
    ext="${file##*.}"

    if [[ $ext != "pkg" ]]; then
        /usr/bin/osascript -e "display alert \"Error: Only .pkg files supported\""
        exit 1
    fi

    if [[ -f "$dest_dir"/"${filename}_signed.pkg" ]]; then
        /usr/bin/osascript -e "display alert \"Error: Target file already exists\""
        exit 1
    fi

    # Sign pkg using certificate found in keychain
    /usr/bin/productsign --sign "Developer ID Installer: <codesigning certificate>" "$file" "$dest_dir"/"${filename}_signed.pkg"
done