Projectile-grep, projectile-ag et al always execute the search in the current file's project.
What I want to do is to select the project from a completion list and get projectile to search that project instead of having to open a file in the project directory and running the search from there.
Does emacs or projectile itself have some way of doing that? The only way I can think of for now is to get the completion dialog to open a buffer onto a file from that project and run the projectile-grep command after that. That seems clumsy some how.