rspreadsheet.gemspec in rspreadsheet-0.4.1 vs rspreadsheet.gemspec in rspreadsheet-0.4.2

@@ -16,15 +16,18 @@
   spec.files         = `git ls-files -z`.split("\x0")
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  def self.package_installed?(pkgname)
-    system("dpkg-query -l #{pkgname} | grep -q '^i'")
+  def self.package_natively_installed?(pkgname)
+    # if the shell fails, the system command returns nil. In that case we assume that the package is NOT installed. It might be overkill, because I am supresing the stderr as well
+    (system("dpkg-query -l #{pkgname} 2>/dev/null | grep -q '^i'")==true) or  # debian based
+    (system("rpm -qa 2>/dev/null | grep -q '#{pkgname}' ")==true) or          # rpm based 
+    (system("pkg_info -q -e #{pkgname} >/dev/null 2>&1")==true)               # openbsd and alike
   end
   
   # runtime dependencies
-  unless package_installed?('ruby-libxml')
+  unless package_natively_installed?('ruby-libxml')
     spec.add_runtime_dependency 'libxml-ruby', '~>2.7'   # parsing XML files
   end
   spec.add_runtime_dependency 'rubyzip', '~>1.1'       # opening zip files
   spec.add_runtime_dependency 'andand', '~>1.3'