Add Manually Pass Two Git Files To Delta as a Unix TIL

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1542 TILs and counting..._
+_1543 TILs and counting..._
 
 ---
 
@@ -1528,6 +1528,7 @@ _1542 TILs and counting..._
 - [Load Env Vars In Bash Script](unix/load-env-vars-in-bash-script.md)
 - [Look Through All Files That Have Been Git Stashed](unix/look-through-all-files-that-have-been-git-stashed.md)
 - [Make Direnv Less Noisy](unix/make-direnv-less-noisy.md)
+- [Manually Pass Two Git Files To Delta](unix/manually-pass-two-git-files-to-delta.md)
 - [Map A Domain To localhost](unix/map-a-domain-to-localhost.md)
 - [Negative Look-Ahead Search With ripgrep](unix/negative-look-ahead-search-with-ripgrep.md)
 - [Occupy A Local Port With Netcat](unix/occupy-a-local-port-with-netcat.md)

unix/manually-pass-two-git-files-to-delta.md

@@ -0,0 +1,32 @@
+# Manually Pass Two Git Files To Delta
+
+I recently [wired up `delta` as my default pager and differ for
+`git`](git/better-diffs-with-delta.md). However, when I installed `delta`, I
+first wanted to see what its diff output looked like.
+
+How can I pass two versions of the same file from `git` to `delta`?
+
+I can show the current contents of a file with `git show` referencing the
+`HEAD` commit.
+
+```bash
+$ git show HEAD:main.go
+```
+
+Similiarly, I can show the contents of that file _one_ commit ago with `HEAD~`.
+
+```bash
+$ git show HEAD~:main.go
+```
+
+I can then pass each of those commands as virtual files to `delta` using the
+`<()` syntax. The older file goes first and the newer second.
+
+```bash
+$ delta <(git show HEAD~:main.go) <(git show HEAD:main.go)
+```
+
+That works and comes in handy if you need to compare two things that aren't
+necessarily files or aren't necessarily under version control. However, in
+hindsight, I'd say it is easier to add delta as the pager and differ and try it
+out directly.