Issue #1882426 by greg.1.anderson: Document new environment variables…

… PHP_INI, DRUSH_INI and PHP_OPTIONS.

README.txt

@@ -190,6 +190,21 @@ Alternately, if you only want to override a few values, copy example.drush.ini
 from the "examples" folder into $HOME/.drush or the folder /etc/drush and edit
 to suit.  See comments in example.drush.ini for more details.
 
+You may also use environment variables to control the php settings that Drush
+will use.  There are three options:
+
+    export PHP_INI='/path/to/php.ini'
+
+    export DRUSH_INI='/path/to/drush.ini'
+
+    export PHP_OPTIONS='-d memory_limit="128M"'
+
+In the case of PHP_INI and DRUSH_INI, these environment variables specify the
+full path to a php.ini or drush.ini file, should you wish to use one that is
+not in one of the standard locations described above.  The PHP_OPTIONS
+environment variable can be used to specify individual options that should
+be passed to php on the command line when Drush is executed.
+
 Drush requires a fairly unrestricted php environment to run in.  In particular,
 you should insure that safe_mode, open_basedir, disable_functions and
 disable_classes are empty.

drush

@@ -88,9 +88,15 @@ for conf_dir in "`dirname "$SELF_PATH"`" /etc/drush $HOME/.drush ; do
     drush_php_override="$conf_dir/drush.ini"
   fi
 done
+# If the PHP_INI environment variable is specified, then tell
+# php to use the php.ini file that it specifies.
 if [ -n "$PHP_INI" ] ; then
   drush_php_ini="$PHP_INI"
 fi
+# If the DRUSH_INI environment variable is specified, then
+# extract all ini variable assignments from it and convert
+# them into php '-d' options. These will override similarly-named
+# options in the php.ini file
 if [ -n "$DRUSH_INI" ] ; then
   drush_php_override="$DRUSH_INI"
 fi
@@ -102,6 +108,9 @@ fi
 if [ -n "$drush_php_override" ] ; then
   php_options=`grep '^[a-z_A-Z0-9.]\+ *=' $drush_php_override | sed -e 's|\([^ =]*\) *= *\(.*\)|\1="\2"|' -e 's| ||g' -e 's|^|-d |' | tr '\n\r' '  '`
 fi
+# If the PHP_OPTIONS environment variable is specified, then
+# its contents will be passed to php on the command line as
+# additional options to use.
 if [ -n "$PHP_OPTIONS" ] ; then
   php_options="$php_options $PHP_OPTIONS"
 fi

examples/example.drush.ini

@@ -12,13 +12,18 @@
 ; php.ini file drush is using by running "drush status".
 ; If the php.ini file shown is your webserver ini
 ; file, then rename this file, example.drush.ini,
-; to drush.ini and copy it to one of the following 
+; to drush.ini and copy it to one of the following
 ; locations:
 ;
 ; 1. Drush installation folder
 ; 2. User's .drush folder (i.e. ~/.drush/drush.ini)
 ; 3. System wide configuration folder (i.e. /etc/drush/drush.ini)
 ;
+; If the environment variable DRUSH_INI is defined,
+; then the file it specified will be used as drush.ini.
+;
+;    export DRUSH_INI='/path/to/drush.ini'
+;
 ; When in use, the variables defined in this file
 ; will override the setting values that appear in
 ; your php.ini file.  See the examples below for
@@ -32,14 +37,18 @@
 ; has the same value as the webserver php.ini
 ; to keep the size of the override list small.
 ;
-; To fully specify the value of all php.ini variables, 
-; copy your webserver php.ini file to one of the 
+; To fully specify the value of all php.ini variables,
+; copy your webserver php.ini file to one of the
 ; locations mentioned above (e.g. /etc/drush/php.ini)
-; and edit it to suit.
+; and edit it to suit.  Alternately, you may use
+; the environment variable PHP_INI to point at
+; the file that Drush should use.
+;
+;    export PHP_INI='/path/to/php.ini'
 ;
 ; The options listed below are particularly relevant
 ; to drush.
-; 
+;
 
 ;
 ; drush needs as much memory as Drupal in order
@@ -64,7 +73,7 @@ display_errors = stderr
 ; sometimes set to restrictive values in a
 ; webserver's php.ini:
 ;
-;safe_mode = 
-;open_basedir = 
+;safe_mode =
+;open_basedir =
 ;disable_functions =
 ;disable_classes =