Updated SC2230 (markdown)

SC2230.md

@@ -11,7 +11,11 @@ which grep
 ### Correct code:
 
 ```sh
+# For the path of a single, unaliased, external command,
+# or to check whether this will just "run" in this shell:
 command -v grep
+# To check whether commands exist, without obtaining a reusable path:
+hash grep
 ```
 
 ### Rationale:
@@ -24,7 +28,9 @@ This check is opt-in only in 0.7.1+, and you may choose to [[ignore]] it in earl
 
 ### Caveats:
 
-With BASH 5.0.7 (via homebrew on macOS 10.13.6), `command -v` appears to take multiple parameters:
+#### `command -v` does not check ALL parameters
+
+`command -v` succeeds (with exit code 0) if *any* command exists:
 
 ```
 # grep is in /usr/bin/grep
@@ -34,9 +40,9 @@ $ command -v -- grep foobar; echo $?
 0
 ```
 
-but succeeds (with exit code 0) if *any* command exists. In the above
+In the above example, it should have failed and exited with 1 unless *all* commands
-example, it should have failed and exited with 1 unless *all* commands
+exist, if it were to be a replacement for `which`. Other problems associated with
-exist.
+`command` include its inclusion of builtins, aliases, and functions.
 
 An alternative is:
 
@@ -46,6 +52,11 @@ $ hash <file1> <file2>
 
 Which observes the standard behaviour of failures.
 
+To obtain a path, `type -p` can be used instead. Like `command -v`, it has a similarly
+quirky behavior with builtins, aliases, and functions, although this is
+arguably milder since it would print nothing for these cases. The failure condition is
+similar to `hash`.
+
 ### Related resources:
 
 * [Check if a program exists from a Bash script](https://stackoverflow.com/a/677212/1899640) on StackOverflow.