diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -407,15 +407,20 @@ class changeset_templater(object):
         '''set template string to use'''
         self.t.cache['changeset'] = t
 
-    def write(self, thing):
+    def write(self, thing, header=False):
         '''write expanded template.
         uses in-order recursive traverse of iterators.'''
         for t in thing:
             if hasattr(t, '__iter__'):
-                self.write(t)
+                self.write(t, header=header)
+            elif header:
+                self.ui.write_header(t)
             else:
                 self.ui.write(t)
 
+    def write_header(self, thing):
+        self.write(thing, header=True)
+
     def show(self, rev=0, changenode=None, brinfo=None):
         '''show a single changeset or file revision'''
         log = self.repo.changelog
@@ -549,6 +554,18 @@ class changeset_templater(object):
             }
 
         try:
+            if self.ui.debugflag and 'header_debug' in self.t:
+                key = 'header_debug'
+            elif self.ui.quiet and 'header_quiet' in self.t:
+                key = 'header_quiet'
+            elif self.ui.verbose and 'header_verbose' in self.t:
+                key = 'header_verbose'
+            elif 'header' in self.t:
+                key = 'header'
+            else:
+                key = ''
+            if key:
+                self.write_header(self.t(key, **props))
             if self.ui.debugflag and 'changeset_debug' in self.t:
                 key = 'changeset_debug'
             elif self.ui.quiet and 'changeset_quiet' in self.t:
@@ -1255,11 +1272,26 @@ def debugancestor(ui, index, rev1, rev2)
     a = r.ancestor(r.lookup(rev1), r.lookup(rev2))
     ui.write("%d:%s\n" % (r.rev(a), hex(a)))
 
-def debugcomplete(ui, cmd):
+def debugcomplete(ui, cmd='', **opts):
     """returns the completion list associated with the given command"""
+
+    if opts['options']:
+        options = []
+        otables = [globalopts]
+        if cmd:
+            aliases, entry = find(cmd)
+            otables.append(entry[1])
+        for t in otables:
+            for o in t:
+                if o[0]:
+                    options.append('-%s' % o[0])
+                options.append('--%s' % o[1])
+        ui.write("%s\n" % "\n".join(options))
+        return
+
     clist = findpossible(cmd).keys()
     clist.sort()
-    ui.write("%s\n" % " ".join(clist))
+    ui.write("%s\n" % "\n".join(clist))
 
 def debugrebuildstate(ui, repo, rev=None):
     """rebuild the dirstate as it would look like for the given revision"""
@@ -1897,9 +1929,11 @@ def log(ui, repo, *pats, **opts):
         def __init__(self, ui):
             self.ui = ui
             self.hunk = {}
+            self.header = {}
         def bump(self, rev):
             self.rev = rev
             self.hunk[rev] = []
+            self.header[rev] = []
         def note(self, *args):
             if self.verbose:
                 self.write(*args)
@@ -1908,6 +1942,8 @@ def log(ui, repo, *pats, **opts):
                 self.write(*args)
         def write(self, *args):
             self.hunk[self.rev].append(args)
+        def write_header(self, *args):
+            self.header[self.rev].append(args)
         def debug(self, *args):
             if self.debugflag:
                 self.write(*args)
@@ -1964,6 +2000,9 @@ def log(ui, repo, *pats, **opts):
                 du.write("\n\n")
         elif st == 'iter':
             if count == limit: break
+            if du.header[rev]:
+                for args in du.header[rev]:
+                    ui.write_header(*args)
             if du.hunk[rev]:
                 count += 1
                 for args in du.hunk[rev]:
@@ -2637,7 +2676,10 @@ def tags(ui, repo):
             r = "%5d:%s" % (repo.changelog.rev(n), hex(n))
         except KeyError:
             r = "    ?:?"
-        ui.write("%-30s %s\n" % (t, r))
+        if ui.quiet:
+            ui.write("%s\n" % t)
+        else:
+            ui.write("%-30s %s\n" % (t, r))
 
 def tip(ui, repo, **opts):
     """show the tip revision
@@ -2814,7 +2856,10 @@ table = {
           ('X', 'exclude', [], _('exclude names matching the given patterns'))],
          _('hg copy [OPTION]... [SOURCE]... DEST')),
     "debugancestor": (debugancestor, [], _('debugancestor INDEX REV1 REV2')),
-    "debugcomplete": (debugcomplete, [], _('debugcomplete CMD')),
+    "debugcomplete":
+        (debugcomplete,
+         [('o', 'options', None, _('show the command options'))],
+         _('debugcomplete [-o] CMD')),
     "debugrebuildstate":
         (debugrebuildstate,
          [('r', 'rev', '', _('revision to rebuild to'))],