diff --git a/README.md b/README.md
index 1c7021c..90b8c4d 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://tinyletter.com/jbranchaud).
 
-_1114 TILs and counting..._
+_1115 TILs and counting..._
 
 ---
 
@@ -1048,6 +1048,7 @@ _1114 TILs and counting..._
 - [Exclude Certain Files From An rsync Run](unix/exclude-certain-files-from-an-rsync-run.md)
 - [Figure Out The Week Of The Year From The Terminal](unix/figure-out-the-week-of-the-year-from-the-terminal.md)
 - [File Type Info With File](unix/file-type-info-with-file.md)
+- [Find A File Installed By Brew](unix/find-a-file-installed-by-brew.md)
 - [Find Files With fd](unix/find-files-with-fd.md)
 - [Find Newer Files](unix/find-newer-files.md)
 - [Fix Unlinked Node Binaries With asdf](unix/fix-unlinked-node-binaries-with-asdf.md)
diff --git a/unix/find-a-file-installed-by-brew.md b/unix/find-a-file-installed-by-brew.md
new file mode 100644
index 0000000..8611567
--- /dev/null
+++ b/unix/find-a-file-installed-by-brew.md
@@ -0,0 +1,33 @@
+# Find A File Installed By Brew
+
+I installed a homebrew formula to satisfy a dependency for a Rails application.
+Related to [the whole mimemagic
+debacle](https://github.com/rails/rails/issues/41750), I had run [`brew install
+shared-mime-info`](https://formulae.brew.sh/formula/shared-mime-info). The
+specific file that Rails needed from this install was `freedesktop.org.xml`.
+
+It took me two commands to figure out if that file had been included and where
+it was living.
+
+The first was to find the _brew prefix directory_ — the place where homebrew
+had installed everything related to `shared-mime-info`.
+
+```bash
+$ brew --prefix shared-mime-info
+/usr/local/opt/shared-mime-info
+```
+
+Now that I know about that directory, I can use
+[`fd`](https://github.com/sharkdp/fd)—a more user-friendly alternative to
+`find`—to _find_ the specific file in that directory. Not wanting to cast too
+narrow of a net, I decided to look for any `xml` file in that directory.
+
+```bash
+$ fd -e xml . /usr/local/opt/shared-mime-info
+/usr/local/opt/shared-mime-info/share/shared-mime-info/packages/freedesktop.org.xml
+```
+
+The `-e` flag specifies the file extension. The `.` is the first argument, the
+pattern to look for. In this case, anything. The second argument
+(`/usr/local/opt/shared-mime-info`) is the path to look within. In this case,
+the brew prefix for the `shared-mime-info` package.