Add Different Ways To Generate A v4 UUID 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).
 
-_1279 TILs and counting..._
+_1280 TILs and counting..._
 
 ---
 
@@ -1222,6 +1222,7 @@ _1279 TILs and counting..._
 - [Curl With Cookies](unix/curl-with-cookies.md)
 - [Curling For Headers](unix/curling-for-headers.md)
 - [Curling With Basic Auth Credentials](unix/curling-with-basic-auth-credentials.md)
+- [Different Ways To Generate A v4 UUID](unix/different-ways-to-generate-a-v4-uuid.md)
 - [Display All The Terminal Colors](unix/display-all-the-terminal-colors.md)
 - [Display Free Disk Space](unix/display-free-disk-space.md)
 - [Display The Contents Of A Directory As A Tree](unix/display-the-contents-of-a-directory-as-a-tree.md)

unix/different-ways-to-generate-a-v4-uuid.md

@@ -0,0 +1,27 @@
+# Different Ways To Generate A v4 UUID
+
+There have been times where I have needed a random UUID. Usually if I am
+mocking some data or testing something out that needs a value in the shape of a
+UUID. Here are a couple different ways to do this in the terminal, as
+one-liners.
+
+With `ruby` and the `SecureRandom` class:
+
+```bash
+$ ruby -e "require 'securerandom'; puts SecureRandom.uuid"
+29e52b97-b43d-4025-a43d-70053b1d1a63
+```
+
+With `psql` and the `gen_random_uuid()` function:
+
+```bash
+$ psql -Xqtc 'select gen_random_uuid()' postgres | xargs
+5a925ebd-c85f-4d94-a81e-e229c4cbe99f
+```
+
+With the `uuidgen` function that ships with Unix/Linux OSs:
+
+```bash
+$ uuidgen
+B11555D8-A256-4EC8-A0B0-9259FF88C3FC
+```