(added => for emphasize )

  DB<200> h
List/search source lines:               Control script execution:
  l [ln|sub]  List source code            T           Stack trace
  - or .      List previous/current line  s [expr]    Single step [in 
+expr]
  v [line]    View around line            n [expr]    Next, steps over
+ subs
  f filename  View source in file         <CR/Enter>  Repeat last n or
+ s
  /pattern/ ?patt?   Search forw/backw    r           Return from subr
+outine
  M           Show module versions        c [ln|sub]  Continue until p
+osition
Debugger controls:                        L           List break/watch
+/actions
  o [...]     Set debugger options        t [n] [expr] Toggle trace [m
+ax depth] ][trace expr]
  <[<]|{[{]|>[>] [cmd] Do pre/post-prompt b [ln|event|sub] [cnd] Set b
+reakpoint
  ! [N|pat]   Redo a previous command     B ln|*      Delete a/all bre
+akpoints
=>H [-num]    Display last num commands   a [ln] cmd  Do cmd before li
+ne
  = [a val]   Define/list an alias        A ln|*      Delete a/all act
+ions
=>h [db_cmd]  Get help on command         w expr      Add a watch expr
+ession
  h h         Complete help page          W expr|*    Delete a/all wat
+ch exprs
  |[|]db_cmd  Send output to pager        ![!] syscmd Run cmd in a sub
+process
  q or ^D     Quit                        R           Attempt a restar
+t
Data Examination:     expr     Execute perl code, also see: s,n,t expr
  x|m expr       Evals expr in list context, dumps the result or lists
+ methods.
  p expr         Print expression (uses script's current package).
  S [[!]pat]     List subroutine names [not] matching pattern
  V [Pk [Vars]]  List Variables in Package.  Vars can be ~pattern or !
+pattern.
  X [Vars]       Same as "V current_package [Vars]".  i class inherita
+nce tree.
  y [n [Vars]]   List lexicals in higher scope <n>.  Vars same as V.
  e     Display thread id     E Display all thread ids.
=> For more help, type h cmd_letter, or run perldoc perldebug for all 
+docs.
  DB<200> h H
H -number    Display last number commands (default all).
H *          Delete complete history.
  DB<201>
[download]

excerpt:

• h [db_cmd] Get help on command
• H [-num] Display last num commands
• For more help, type h cmd_letter or run perldoc perldebug for all docs.
• > h H
  H * Delete complete history.