Cron issue with Drush 8 My Drupal 6 sites are hosted on a Linux server with Apache 2.2, PHP 5.5, MySQL 5.6 installed. I use Drush 8 which I installed via composer. 
I set a cron job via cPanel which runs every day this script:

#!/bin/bash
# Script to execute all the cron jobs with drush
echo '**************** French site *******************'
cd /home/myuser/public_html/fr/sites/fr.mysite.com
/home/myuser/.composer/vendor/bin/drush -v core-cron
echo '**************** English site ******************'
cd /home/myuser/public_html/en/sites/en.mysite.com
/home/myuser/.composer/vendor/bin/drush -v core-cron
echo '**************** Spanish site ******************'
cd /home/myuser/public_html/es/sites/es.mysite.com
/home/myuser/.composer/vendor/bin/drush -v core-cron
echo '**************** Completed **********************'


But it fails and ends with:

**************** French site *******************
X-Powered-By: PHP/5.5.33
Content-type: text/html

&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_open(): Descriptor item must be either an array or a File-Handle in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;434&lt;/b&gt;&lt;br /&gt;
&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_get_status() expects parameter 1 to be resource, boolean given in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;435&lt;/b&gt;&lt;br /&gt;
&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_close() expects parameter 1 to be resource, boolean given in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;436&lt;/b&gt;&lt;br /&gt;
**************** English site ******************
X-Powered-By: PHP/5.5.33
Content-type: text/html

&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_open(): Descriptor item must be either an array or a File-Handle in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;434&lt;/b&gt;&lt;br /&gt;
&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_get_status() expects parameter 1 to be resource, boolean given in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;435&lt;/b&gt;&lt;br /&gt;
&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_close() expects parameter 1 to be resource, boolean given in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;436&lt;/b&gt;&lt;br /&gt;
**************** Spanish site ******************
X-Powered-By: PHP/5.5.33
Content-type: text/html

&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_open(): Descriptor item must be either an array or a File-Handle in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;434&lt;/b&gt;&lt;br /&gt;
&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_get_status() expects parameter 1 to be resource, boolean given in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;435&lt;/b&gt;&lt;br /&gt;
&lt;br /&gt;
&lt;b&gt;Warning&lt;/b&gt;:  proc_close() expects parameter 1 to be resource, boolean given in &lt;b&gt;/home/myuser/.composer/vendor/drush/drush/includes/startup.inc&lt;/b&gt; on line &lt;b&gt;436&lt;/b&gt;&lt;br /&gt;
**************** Completed **********************


The strange thing is that when I manually run drush -v core-cron on any site, the cron run ends successfully. I really don't know where the problem comes from.
I would suggest that instead of calling cd within your script, you either set up drush aliases or pass the --root and --uri parameters to the cron request. 

/home/myuser/.composer/vendor/bin/drush -v --root=/home/myuser/public_html --uri=fr.mysite.com core-cron


That should make sure that drush is running in the right context. 

You can also make sure that drush is running with the php that you would like by setting the DRUSH_PHP environment variable.