Add Different Ways To Generate A v4 UUID as a Unix TIL

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

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+# 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
+```