Add Clean Up Your Brew Installations as a Brew TIL

README.md

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 ### Brew
 
+- [Clean Up Your Brew Installations](brew/clean-up-your-brew-installations.md)
 - [Configure Brew Environment Variables](brew/configure-brew-environment-variables.md)
 - [Export List Of Everything Installed By Brew](brew/export-list-of-everything-installed-by-brew.md)
 - [List All Services Managed By Brew](brew/list-all-services-managed-by-brew.md)

brew/clean-up-your-brew-installations.md

@@ -0,0 +1,40 @@
+# Clean Up Your Brew Installations
+
+Over time as you upgrade brew-installed programs and make changes to your
+`Brewfile`, your machine will have artifacts left behind that you no longer
+need.
+
+Periodically, it is good to clean things up.
+
+First, you can get a summary of stale and outdated files that brew has
+installed. Use the `--dry-run` flag.
+
+```bash
+$ brew cleanup --dry-run
+```
+
+If you feel good about what you see in the output, then give things a clean.
+
+```bash
+$ brew cleanup
+```
+
+Second, if you are using a `Brewfile` to manage what `brew` installs, then you
+can instruct `brew` to uninstall any dependencies that aren't specified in that
+file.
+
+By default it operates as a dry run and the `--force` flag will be needed to
+actually do the cleanup. And specify the filename if it doesn't match the
+default of `Brewfile`.
+
+```bash
+$ brew bundle cleanup --file=Brewfile.personal
+```
+
+If the output looks good, then force the cleanup:
+
+```bash
+$ brew bundle cleanup --force --file=Brewfile.personal
+```
+
+See `brew cleanup --help` and `brew bundle --help` for more details.