IF [NOT][WARN][ERROR][FAIL][EXISTS file]

* The IF command allows conditional execution of statements
  following it.
* If the condition specified is true, then execution continues
  after the IF statement until either an  ENDIF  or  ELSE  statement
  is encountered. If it is an ELSE statement, then all statements
  between the ELSE and the closing ENDIF are skipped.
* If the condition is false, then all statements after the IF and
  before either an  ENDIF  or  ELSE  statement are skipped. If an ELSE
  is encountered, then execution continues for all statements after
  the ELSE and before the closing ENDIF.
* IF can examine the state of the return code from the last command
  execute with WARN, ERROR, and FAIL tests. You can test for the
  non existence of such a state by including the optional NOT
  parameter.

eg.     IF WARN
           echo "last command returned warnings"
        ELSE
           echo "last command did not return warnings"
        ENDIF

        IF NOT FAIL
           echo "last command did not fail"
        ENDIF

* IF can also test for the existence of a file or directory.

eg.     IF EXISTS :system/format
           echo "this disk has a format command"
           echo "you can look yourself. I'm not joking"
        ENDIF

        IF NOT EXISTS ram:ed
           copy c:ed ram:
        ENDIF