From 9773f10b8471aa4fd3abce04d6e1d1da6b2eb1d0 Mon Sep 17 00:00:00 2001
From: jbranchaud <jbranchaud@gmail.com>
Date: Thu, 15 Jan 2026 08:32:41 -0600
Subject: [PATCH] Add Use Negative Lookbehind Matching With ripgrep as a Unix
 TIL

---
 README.md                                     |  3 +-
 ...gative-lookbehind-matching-with-ripgrep.md | 42 +++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 unix/use-negative-lookbehind-matching-with-ripgrep.md

diff --git a/README.md b/README.md
index 7e61b3e..50fa8d1 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ working across different projects via [VisualMode](https://www.visualmode.dev/).
 
 For a steady stream of TILs, [sign up for my newsletter](https://visualmode.kit.com/newsletter).
 
-_1728 TILs and counting..._
+_1729 TILs and counting..._
 
 See some of the other learning resources I work on:
 
@@ -1773,6 +1773,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Unrestrict Where ripgrep Searches](unix/unrestrict-where-ripgrep-searches.md)
 - [Update Package Versions Known By asdf Plugin](unix/update-package-versions-known-by-asdf-plugin.md)
 - [Use fzf To Change Directories](unix/use-fzf-to-change-directories.md)
+- [Use Negative Lookbehind Matching With ripgrep](unix/use-negative-lookbehind-matching-with-ripgrep.md)
 - [Use Regex Pattern Matching With Grep](unix/use-regex-pattern-matching-with-grep.md)
 - [View A Web Page In The Terminal](unix/view-a-web-page-in-the-terminal.md)
 - [View The Source For A Brew Formula](unix/view-the-source-for-a-brew-formula.md)
diff --git a/unix/use-negative-lookbehind-matching-with-ripgrep.md b/unix/use-negative-lookbehind-matching-with-ripgrep.md
new file mode 100644
index 0000000..0656dd3
--- /dev/null
+++ b/unix/use-negative-lookbehind-matching-with-ripgrep.md
@@ -0,0 +1,42 @@
+# Use Negative Lookbehind Matching With ripgrep
+
+The most straightforward way to use `ripgrep` is to hand it a pattern. It will
+take that pattern and move forward through each file trying to find matches.
+
+```bash
+$ rg 'TwilioClient\.new'
+```
+
+That will find all occurrences of `TwilioClient.new` in available project files.
+
+What if that pattern is too permissive though? That is going to match on
+occurrences of `TwilioClient.new` as well as things like
+`LoggingTwilioClient.new`. If we want to exclude the latter, there are a few
+ways to do that. One of them being the use of [the _negative lookbehind_ regex
+feature](https://www.pcre.org/current/doc/html/pcre2syntax.html#SEC23) that is
+available with PCRE2 (Perl-Compatible Regular Expressions).
+
+A _negative lookbehind_ is like a standard pattern. We look forward through the
+document for the base pattern (like `TwilioClient\.new`). However, once we find
+that match, we then look back at the previous characters and if they match our
+negative lookbehind pattern, then it is no longer a positive match.
+
+We can use one of the following to forms to achieve this:
+
+```
+  (?<!...)                    )
+  (*nlb:...)                  ) negative lookbehind
+  (*negative_lookbehind:...)  )
+```
+
+For instance, here is what this looks like for our example:
+
+```bash
+$ rg -P '(?<!Logging)TwilioClient\.new'
+```
+
+Note: we have to use the `-P` flag to tell `ripgrep` that we are using PCRE2
+syntax. Otherwise, it assumes a simpler regex syntax that doesn't support
+_negative lookbehind_.
+
+See `man rg` for more details.