title: unable to edit pg_hba.conf file in Postgresql
body: <p>I want to create a backup of the original pg_hba.conf file (may be as pg_hba.conf.bk) and then add an entry into the existing pg_hba.conf file. So far this is what i've been trying to do, but every time it says permission denied even if i go via root user or use sudo.</p>
  
  <p>My attempt:</p>
  
  <pre><code>$ pg_conftool -s 10 main show hba_file
  [OUT] /etc/postgresql/10/main/pg_hba.conf
  
  $ sudo cat /etc/postgresql/10/main/pg_hba.conf
      [OUT] local   all             postgres                              peer
            local   all             all                                   md5
            host    all             all             127.0.0.1/32          md5
            host    all             all             ::1/128               md5
  </code></pre>
  
  <p>now when i try adding a line into it, i get the permission denied error</p>
  
  <pre><code>$ sudo echo "host all all 0.0.0.0/0 trust" &gt;&gt; /etc/postgresql/10/main/pg_hba.conf
  [OUT] bash: /etc/postgresql/10/main/pg_hba.conf: Permission denied
  </code></pre>
  
  <p>This will be a part of deployment script therefore, I can't really go and make the entry into the pg_hba.conf manually. So, how can i make an entry into the conf file? </p>