title: Bash Script - How take a result of command and use it
body: <p>I would like to know how to do this, if for example, when executing a command in a script, retrieve the message linked to this command.
  For example &quot;AZERTY already exists, please check the error&quot; is the message that comes out after a command (wrong), how do I so that if my BASH script sees this info, tell it to stop the script?</p>