Mention $_ in 'Elegant bash conditionals' post

content/blog/2021-03-02_elegant-bash-conditionals/index.md

@@ -158,6 +158,12 @@ it is empty, so you won't even need conditionals.
 Most other shells support similar operators. [fish][fish] uses `; and` and `;
 or`, but now [supports][fish-and-and] `&&` and `||` as well in modern versions.
 
+`$_` (or `Alt+.`) is your last used argument (thanks [@Diti](https://lobste.rs/u/Diti)). For example:
+
+```bash
+test -f FILE && source $_ || echo "FILE does not exist" >&2
+```
+
 ## Closing thoughts
 These command sequences with control operators are an elegant alternative for
 simple if-statements. I think they look much better and are more expressive