Drush can't find php I am on a shared server and someone else has installed Drush previously. But as of now Drush does not work and throws the following error.

[root@vps1]# drush
/root/.composer/vendor/bin/drush: line 47: which: command not found
ERROR: can't find php.


The last thing I can remember was updating PHP (mod_php) to 5.4.36 several days ago. It worked on 5.4.34, but PHP was recompiled during the update. Is this related? What do I need to do to tell drush about this 'new' php?
which: command not found


I don't really use Drush,  but that looks like it's dying when it uses the "which" command to locate PHP...  Drush is falsely reporting that PHP can't be found,  but it's because the command it uses to look for it ("which") is not available.