Add Generate Random 20-Character Hex String as a Unix TIL

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).
 
-_1342 TILs and counting..._
+_1343 TILs and counting..._
 
 ---
 
@@ -1289,6 +1289,7 @@ _1342 TILs and counting..._
 - [Fix Unlinked Node Binaries With asdf](unix/fix-unlinked-node-binaries-with-asdf.md)
 - [Forward Multiple Ports Over SSH](unix/forward-multiple-ports-over-ssh.md)
 - [Generate A SAML Key And Certificate Pair](unix/generate-a-saml-key-and-certificate-pair.md)
+- [Generate Random 20-Character Hex String](unix/generate-random-20-character-hex-string.md)
 - [Get Matching Filenames As Output From Grep](unix/get-matching-filenames-as-output-from-grep.md)
 - [Get The Unix Timestamp](unix/get-the-unix-timestamp.md)
 - [Global Substitution On The Previous Command](unix/global-substitution-on-the-previous-command.md)

unix/generate-random-20-character-hex-string.md

@@ -0,0 +1,17 @@
+# Generate Random 20-Character Hex String
+
+The `openssl` utility has a bunch of subcommands including `rand`. The `rand`
+subcommand can be used to generate pseudo-random numbers.
+
+```bash
+openssl rand -hex 10
+5ce459896581abc81a65
+```
+
+The number at the end of the command tells `rand` how many bytes of output to
+generate. When the `-hex` flag is used, it will encode the output in hex.
+
+The 10 bytes of output in hex will result in a 20-character string. That number
+can be adjusted to your needs.
+
+See `man openssl` or `openssl rand -help` for more details.