title: systemctl start service does not work in SPEC file
body: <p>I met a problem that the command "sudo systemctl start xxx.service" in my SPEC file does not work when upgrading my RPM package, following is my %post script in SPEC file,</p>
  
  <pre><code>%post
  echo "---------------------------- post $1 -------------------------------"
  # refresh installation
  if [ $1 == 1 ]; then
    sudo echo "Installation finished."
  # upgrade installation
  elif [ $1 -gt 1 ]; then
    sudo echo "Starting service xxx.service..."
    sudo /usr/bin/systemctl enable xxx.service &gt; /dev/null 2&gt;&amp;1
    sudo /usr/bin/systemctl start xxx.service
    sleep 10
    sudo echo "Finished."
  fi
  exit 0
  </code></pre>
  
  <p>I'm sure that the service file already exists in directory /usr/lib/systemd/system, and I can start it manually using the command "sudo systemctl start xxx.service".</p>
  
  <p>And I found that the "sleep 10" command does not work too.</p>
  
  <p>Very appreciated if there is any suggestion about this issue, thanks.</p>