Have I mentioned that I love Linux and the awesome little tools it comes with? Granted vimgrep is not a “Linux” tool itself but rather a function used within vim to do a recursive search throughout a folder structure.
Ensure you are at the root of your project in Vim. Then type in “:pwd” in vim to see if what dir you are in and then, type in “:cd /path/to/project”. Lastly, type “:vimgrep pattern */.php”. Voilà! Pattern found.