Note about exit code

SC2005.md

@@ -20,6 +20,8 @@ cat 1.txt # In bash, but faster and still sticks exactly one newline: printf '%s
 
 The command substitution `$(foo)` yields the result of command `foo` with trailing newlines erased, and when it is passed to `echo` it generally just gives the same result as `foo`. 
 
+The command `echo "$(false)"` will return true, whereas `false` of course returns false – beware of the ignored exit code before blindly altering scripts. If using `set -e`, the correct substitution of `echo "$(cmd)"` would be `cmd || true`.
+
 ### Exceptions
 
 One may want to use command substitutions plus `echo` to make sure there is exactly one trailing newline. The special command substitution `$(<file)` in `bash` is also un-outline-able.