[DEVX-3831] Allow PHP binary to be selected via an environment variable.

[greg-1-anderson]

Create a bash wrapper that allows users to select a specific PHP version via an environment variable.

For users who install the terminus.phar binary by the existing documented approach, there is no change in behavior; the old way continues to work, but does not allow the PHP binary to be selected (only the one in the $PATH may be used).

For users who install the new terminus script in their $PATH, and also put terminus.phar in their $PATH (without renaming it), the following behavior is now supported:

$ php --version
PHP 7.4.33 (cli) (built: Nov 22 2024 10:43:27) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.33, Copyright (c), by Zend Technologies
$ terminus --version

Sorry, your PHP version (7.4.33) is no longer supported.
Upgrade to PHP 8.2 or newer to use Terminus 4. For PHP versions prior to 8.2, downgrade to Terminus 3.x.

For more information, see https://pantheon.io/docs/terminus/updates#php-version-compatibility-matrix
$ export TERMINUS_PHP=/opt/homebrew/Cellar/[email protected]/8.3.14/bin/php
$ $TERMINUS_PHP --version
PHP 8.3.14 (cli) (built: Nov 19 2024 15:14:23) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.3.14, Copyright (c) Zend Technologies
    with Zend OPcache v8.3.14, Copyright (c), by Zend Technologies
$ terminus --version
Terminus 4.0.0-dev

[greg-1-anderson]

Simple terminus wrapper script:

#!/usr/bin/env sh

SCRIPTPATH="$( cd -- "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"

TERMINUS_EXECUTABLE="$SCRIPTPATH/terminus.php"

# If we can't find `terminus.php` next to `terminus`,
# look for `terminus.php` in the same directory.
if [ ! -f "$TERMINUS_EXECUTABLE" ]; then
  TERMINUS_EXECUTABLE="$SCRIPTPATH/terminus.phar"
fi

# If there is no `terminus.phar` nearby, check for one
# in the $PATH.
if [ ! -f "$TERMINUS_EXECUTABLE" ]; then
  TERMINUS_EXECUTABLE="terminus.phar"
fi

# Use the PHP binary indicated by $TERMINUS_PHP, or use
# the one in the $PATH if $TERMINUS_PHP is not set.
PHP="${TERMINUS_PHP=php}"

# Run Terminus with the selected version of PHP, passing
# through all parameters.
exec "$TERMINUS_PHP" "$TERMINUS_EXECUTABLE" "$@"