How to use another php version for drush 9? On live server I use differents drush and php versions for drupal 8.4 and 7.
I install drush 9 to ~/drush9 directory with composer require drush/drush:9.* command.

On dev server and drupal 8.4 I use site.alias.yml file for drush 9:

live:
  host: hostingexample.com
  user: user
  root: /home/user/example.com/public_html/
  uri: http://example.com/
  paths:
    drush-script: '/opt/php70/bin/php /home/user/drush9/vendor/bin/drush'


And for command drush @site.live ev 'print PHP_VERSION' have an error: bash: /opt/php70/bin/php /home/user/drush9/vendor/bin/drush: No such file or directory

If I add

alias php=/opt/php70/bin/php
alias drush9=~/drush9/vendor/bin/drush


in hosting .bash_profile and change drush-script: '/home/user/drush9/vendor/bin/drush' in site.alias.yml. And have an error PHP Parse error:  syntax error, unexpected '[' in /home/user/drush9/vendor/drush/drush/src/Config/Environment.php on line 98. Because on hosting default php version is 5.3.

How to use another php version for hosting and config it for drush 9 aliases?
Try editing both the .bash_rc and .bash_profile files so that you include the directory where the version of PHP you want is FIRST (before existing PATH):

(add this line or adjust if existing):

export PATH="/opt/php70/bin:$PATH"

As a last ditch effort, you can set the env variable drush looks for as well in these files:

DRUSH_PHP=/opt/php70/bin/php