diff --git a/src/TDB2.cpp b/src/TDB2.cpp
index 0148a51e6..02f41e698 100644
--- a/src/TDB2.cpp
+++ b/src/TDB2.cpp
@@ -584,7 +584,7 @@ void TDB2::add (Task& task, bool add_to_backlog /* = true */)
   if (add_to_backlog)
     context.hooks.onAdd (task);
 
-  update (uuid, task, add_to_backlog, true);
+  update (task, add_to_backlog, true);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -602,12 +602,11 @@ void TDB2::modify (Task& task, bool add_to_backlog /* = true */)
     context.hooks.onModify (original, task);
   }
 
-  update (uuid, task, add_to_backlog);
+  update (task, add_to_backlog);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 void TDB2::update (
-  const std::string& uuid,
   Task& task,
   const bool add_to_backlog,
   const bool addition /* = false */)
@@ -775,10 +774,10 @@ void TDB2::revert ()
 
     // Modify other data files accordingly.
     std::vector <std::string> p = pending.get_lines ();
-    revert_pending (p, uuid, current, prior);
+    revert_pending (p, uuid, prior);
 
     std::vector <std::string> c = completed.get_lines ();
-    revert_completed (p, c, uuid, current, prior);
+    revert_completed (p, c, uuid, prior);
 
     std::vector <std::string> b = backlog.get_lines ();
     revert_backlog (b, uuid, current, prior);
@@ -837,7 +836,6 @@ void TDB2::revert_undo (
 void TDB2::revert_pending (
   std::vector <std::string>& p,
   const std::string& uuid,
-  const std::string& current,
   const std::string& prior)
 {
   std::string uuid_att = "uuid:\"" + uuid + "\"";
@@ -871,7 +869,6 @@ void TDB2::revert_completed (
   std::vector <std::string>& p,
   std::vector <std::string>& c,
   const std::string& uuid,
-  const std::string& current,
   const std::string& prior)
 {
   std::string uuid_att = "uuid:\"" + uuid + "\"";
diff --git a/src/TDB2.h b/src/TDB2.h
index c72b0c528..4353a4ee5 100644
--- a/src/TDB2.h
+++ b/src/TDB2.h
@@ -138,12 +138,12 @@ public:
 
 private:
   void gather_changes ();
-  void update (const std::string&, Task&, const bool, const bool addition = false);
+  void update (Task&, const bool, const bool addition = false);
   bool verifyUniqueUUID (const std::string&);
   void show_diff (const std::string&, const std::string&, const std::string&);
   void revert_undo (std::vector <std::string>&, std::string&, std::string&, std::string&, std::string&);
-  void revert_pending (std::vector <std::string>&, const std::string&, const std::string&, const std::string&);
-  void revert_completed (std::vector <std::string>&, std::vector <std::string>&, const std::string&, const std::string&, const std::string&);
+  void revert_pending (std::vector <std::string>&, const std::string&, const std::string&);
+  void revert_completed (std::vector <std::string>&, std::vector <std::string>&, const std::string&, const std::string&);
   void revert_backlog (std::vector <std::string>&, const std::string&, const std::string&, const std::string&);
 
 public:
diff --git a/src/calc.cpp b/src/calc.cpp
index c22d3c2d2..e9056489e 100644
--- a/src/calc.cpp
+++ b/src/calc.cpp
@@ -39,7 +39,7 @@ Context context;
 
 ////////////////////////////////////////////////////////////////////////////////
 // Constants.
-bool get (const std::string& name, Variant& value)
+bool get (const std::string&, Variant&)
 {
 /*
   // An example, although a bad one because this is supported by default.
diff --git a/src/columns/ColMask.cpp b/src/columns/ColMask.cpp
index a00eb31c3..53b0dfa77 100644
--- a/src/columns/ColMask.cpp
+++ b/src/columns/ColMask.cpp
@@ -68,7 +68,7 @@ void ColumnMask::measure (Task& task, unsigned int& minimum, unsigned int& maxim
 void ColumnMask::render (
   std::vector <std::string>& lines,
   Task& task,
-  int width,
+  int,
   Color& color)
 {
   if (task.has (_name))
diff --git a/src/commands/CmdAnnotate.cpp b/src/commands/CmdAnnotate.cpp
index 7709bfc13..b916c58b5 100644
--- a/src/commands/CmdAnnotate.cpp
+++ b/src/commands/CmdAnnotate.cpp
@@ -53,7 +53,7 @@ CmdAnnotate::CmdAnnotate ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdAnnotate::execute (std::string& output)
+int CmdAnnotate::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -84,7 +84,7 @@ int CmdAnnotate::execute (std::string& output)
 
     task.modify (Task::modAnnotate, true);
 
-    if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+    if (permission (taskDifferences (before, task) + question, filtered.size ()))
     {
       context.tdb2.modify (task);
       ++count;
diff --git a/src/commands/CmdAppend.cpp b/src/commands/CmdAppend.cpp
index b2db54890..15221d6f9 100644
--- a/src/commands/CmdAppend.cpp
+++ b/src/commands/CmdAppend.cpp
@@ -53,7 +53,7 @@ CmdAppend::CmdAppend ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdAppend::execute (std::string& output)
+int CmdAppend::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -84,7 +84,7 @@ int CmdAppend::execute (std::string& output)
 
     task.modify (Task::modAppend, true);
 
-    if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+    if (permission (taskDifferences (before, task) + question, filtered.size ()))
     {
       context.tdb2.modify (task);
       ++count;
diff --git a/src/commands/CmdContext.cpp b/src/commands/CmdContext.cpp
index 9a335b120..ac168bd5b 100644
--- a/src/commands/CmdContext.cpp
+++ b/src/commands/CmdContext.cpp
@@ -68,9 +68,9 @@ int CmdContext::execute (std::string& output)
 
          if (subcommand == "define") rc = defineContext (words, out);
     else if (subcommand == "delete") rc = deleteContext (words, out);
-    else if (subcommand == "list")   rc = listContexts (words, out);
-    else if (subcommand == "none")   rc = unsetContext (words, out);
-    else if (subcommand == "show")   rc = showContext (words, out);
+    else if (subcommand == "list")   rc = listContexts (out);
+    else if (subcommand == "none")   rc = unsetContext (out);
+    else if (subcommand == "show")   rc = showContext (out);
     else                             rc = setContext (words, out);
   }
 
@@ -229,7 +229,7 @@ int CmdContext::deleteContext (const std::vector <std::string>& words, std::stri
 // Invoked with: task context list
 // Example:      task context list
 //
-int CmdContext::listContexts (const std::vector <std::string>& words, std::stringstream& out)
+int CmdContext::listContexts (std::stringstream& out)
 {
   int rc = 0;
   std::vector <std::string> contexts = getContexts();
@@ -321,7 +321,7 @@ int CmdContext::setContext (const std::vector <std::string>& words, std::strings
 // Invoked with: task context show
 // Example:      task context show
 //
-int CmdContext::showContext (const std::vector <std::string>& words, std::stringstream& out)
+int CmdContext::showContext (std::stringstream& out)
 {
   std::string currentContext = context.config.get ("context");
 
@@ -346,7 +346,7 @@ int CmdContext::showContext (const std::vector <std::string>& words, std::string
 // Invoked with: task context none
 // Example:      task context none
 //
-int CmdContext::unsetContext (const std::vector <std::string>& words, std::stringstream& out)
+int CmdContext::unsetContext (std::stringstream& out)
 {
   int rc = 0;
   int status = CmdConfig::unsetConfigVariable ("context", false);
diff --git a/src/commands/CmdContext.h b/src/commands/CmdContext.h
index d06b8f934..414b39dce 100644
--- a/src/commands/CmdContext.h
+++ b/src/commands/CmdContext.h
@@ -35,14 +35,14 @@ class CmdContext : public Command
 public:
   CmdContext ();
   int execute (std::string&);
-  std::string joinWords (const std::vector <std::string>& words, unsigned int from, unsigned int to = 0);
+  std::string joinWords (const std::vector <std::string>&, unsigned int, unsigned int = 0);
   static std::vector <std::string> getContexts ();
-  int defineContext (const std::vector <std::string>& words, std::stringstream& out);
-  int deleteContext (const std::vector <std::string>& words, std::stringstream& out);
-  int listContexts (const std::vector <std::string>& words, std::stringstream& out);
-  int setContext (const std::vector <std::string>& words, std::stringstream& out);
-  int showContext (const std::vector <std::string>& words, std::stringstream& out);
-  int unsetContext (const std::vector <std::string>& words, std::stringstream& out);
+  int defineContext (const std::vector <std::string>&, std::stringstream&);
+  int deleteContext (const std::vector <std::string>&, std::stringstream&);
+  int listContexts (std::stringstream&);
+  int setContext (const std::vector <std::string>&, std::stringstream&);
+  int showContext (std::stringstream&);
+  int unsetContext (std::stringstream&);
 };
 
 class CmdCompletionContext : public Command
diff --git a/src/commands/CmdDelete.cpp b/src/commands/CmdDelete.cpp
index df03e3c8c..1523f0fe1 100644
--- a/src/commands/CmdDelete.cpp
+++ b/src/commands/CmdDelete.cpp
@@ -54,7 +54,7 @@ CmdDelete::CmdDelete ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdDelete::execute (std::string& output)
+int CmdDelete::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -94,7 +94,7 @@ int CmdDelete::execute (std::string& output)
       if (! task.has ("end"))
         task.setAsNow ("end");
 
-      if (permission (task, question, filtered.size ()))
+      if (permission (question, filtered.size ()))
       {
         updateRecurrenceMask (task);
         ++count;
diff --git a/src/commands/CmdDenotate.cpp b/src/commands/CmdDenotate.cpp
index 88c6bbe7c..b4e0706f2 100644
--- a/src/commands/CmdDenotate.cpp
+++ b/src/commands/CmdDenotate.cpp
@@ -53,7 +53,7 @@ CmdDenotate::CmdDenotate ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdDenotate::execute (std::string& output)
+int CmdDenotate::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -130,7 +130,7 @@ int CmdDenotate::execute (std::string& output)
                                      task.id,
                                      task.get ("description"));
 
-      if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+      if (permission (taskDifferences (before, task) + question, filtered.size ()))
       {
         ++count;
         context.tdb2.modify (task);
diff --git a/src/commands/CmdDone.cpp b/src/commands/CmdDone.cpp
index 805c3b8c7..8556216e6 100644
--- a/src/commands/CmdDone.cpp
+++ b/src/commands/CmdDone.cpp
@@ -53,7 +53,7 @@ CmdDone::CmdDone ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdDone::execute (std::string& output)
+int CmdDone::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -97,7 +97,7 @@ int CmdDone::execute (std::string& output)
           task.addAnnotation (context.config.get ("journal.time.stop.annotation"));
       }
 
-      if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+      if (permission (taskDifferences (before, task) + question, filtered.size ()))
       {
         updateRecurrenceMask (task);
         context.tdb2.modify (task);
diff --git a/src/commands/CmdDuplicate.cpp b/src/commands/CmdDuplicate.cpp
index 3aa90449a..2eb555724 100644
--- a/src/commands/CmdDuplicate.cpp
+++ b/src/commands/CmdDuplicate.cpp
@@ -53,7 +53,7 @@ CmdDuplicate::CmdDuplicate ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdDuplicate::execute (std::string& output)
+int CmdDuplicate::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -105,8 +105,7 @@ int CmdDuplicate::execute (std::string& output)
 
     dup.modify (Task::modAnnotate);
 
-    if (permission (dup,
-                    format (STRING_CMD_DUPLICATE_CONFIRM,
+    if (permission (format (STRING_CMD_DUPLICATE_CONFIRM,
                             task.id,
                             task.get ("description")),
                     filtered.size ()))
diff --git a/src/commands/CmdEdit.cpp b/src/commands/CmdEdit.cpp
index 5aa070d90..7cb3b7109 100644
--- a/src/commands/CmdEdit.cpp
+++ b/src/commands/CmdEdit.cpp
@@ -65,7 +65,7 @@ CmdEdit::CmdEdit ()
 // Introducing the Silver Bullet.  This feature is the catch-all fixative for
 // various other ills.  This is like opening up the hood and going in with a
 // wrench.  To be used sparingly.
-int CmdEdit::execute (std::string& output)
+int CmdEdit::execute (std::string&)
 {
   // Filter the tasks.
   handleRecurrence ();
diff --git a/src/commands/CmdExec.cpp b/src/commands/CmdExec.cpp
index 10e860004..ca50ca029 100644
--- a/src/commands/CmdExec.cpp
+++ b/src/commands/CmdExec.cpp
@@ -50,7 +50,7 @@ CmdExec::CmdExec ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdExec::execute (std::string& output)
+int CmdExec::execute (std::string&)
 {
   std::string command_line;
   join (command_line, " ", context.cli2.getWords ());
diff --git a/src/commands/CmdImport.cpp b/src/commands/CmdImport.cpp
index df48db9f5..ed84190f2 100644
--- a/src/commands/CmdImport.cpp
+++ b/src/commands/CmdImport.cpp
@@ -55,7 +55,7 @@ CmdImport::CmdImport ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdImport::execute (std::string& output)
+int CmdImport::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
diff --git a/src/commands/CmdModify.cpp b/src/commands/CmdModify.cpp
index 9f9626aa4..7fea872b1 100644
--- a/src/commands/CmdModify.cpp
+++ b/src/commands/CmdModify.cpp
@@ -53,7 +53,7 @@ CmdModify::CmdModify ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdModify::execute (std::string& output)
+int CmdModify::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -91,7 +91,7 @@ int CmdModify::execute (std::string& output)
                            task.get ("uuid"),
                            task.get ("description"));
 
-      if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+      if (permission (taskDifferences (before, task) + question, filtered.size ()))
       {
         count += modifyAndUpdate (before, task, &projectChanges);
       }
diff --git a/src/commands/CmdPrepend.cpp b/src/commands/CmdPrepend.cpp
index e9d1596b6..d3a8cba14 100644
--- a/src/commands/CmdPrepend.cpp
+++ b/src/commands/CmdPrepend.cpp
@@ -53,7 +53,7 @@ CmdPrepend::CmdPrepend ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdPrepend::execute (std::string& output)
+int CmdPrepend::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -84,7 +84,7 @@ int CmdPrepend::execute (std::string& output)
 
     task.modify (Task::modPrepend, true);
 
-    if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+    if (permission (taskDifferences (before, task) + question, filtered.size ()))
     {
       context.tdb2.modify (task);
       ++count;
diff --git a/src/commands/CmdStart.cpp b/src/commands/CmdStart.cpp
index 4db72bb22..da1690b52 100644
--- a/src/commands/CmdStart.cpp
+++ b/src/commands/CmdStart.cpp
@@ -53,7 +53,7 @@ CmdStart::CmdStart ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdStart::execute (std::string& output)
+int CmdStart::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -95,7 +95,7 @@ int CmdStart::execute (std::string& output)
       if (context.config.getBoolean ("journal.time"))
         task.addAnnotation (context.config.get ("journal.time.start.annotation"));
 
-      if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+      if (permission (taskDifferences (before, task) + question, filtered.size ()))
       {
         updateRecurrenceMask (task);
         context.tdb2.modify (task);
diff --git a/src/commands/CmdStop.cpp b/src/commands/CmdStop.cpp
index feb55a38b..7ca2638e0 100644
--- a/src/commands/CmdStop.cpp
+++ b/src/commands/CmdStop.cpp
@@ -52,7 +52,7 @@ CmdStop::CmdStop ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdStop::execute (std::string& output)
+int CmdStop::execute (std::string&)
 {
   int rc = 0;
   int count = 0;
@@ -87,7 +87,7 @@ int CmdStop::execute (std::string& output)
       if (context.config.getBoolean ("journal.time"))
         task.addAnnotation (context.config.get ("journal.time.stop.annotation"));
 
-      if (permission (task, taskDifferences (before, task) + question, filtered.size ()))
+      if (permission (taskDifferences (before, task) + question, filtered.size ()))
       {
         updateRecurrenceMask (task);
         context.tdb2.modify (task);
diff --git a/src/commands/CmdUndo.cpp b/src/commands/CmdUndo.cpp
index 484353a10..6ec119407 100644
--- a/src/commands/CmdUndo.cpp
+++ b/src/commands/CmdUndo.cpp
@@ -49,7 +49,7 @@ CmdUndo::CmdUndo ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdUndo::execute (std::string& output)
+int CmdUndo::execute (std::string&)
 {
   context.tdb2.revert ();
   return 0;
diff --git a/src/commands/CmdUnique.cpp b/src/commands/CmdUnique.cpp
index 3a2fca135..3a5099c61 100644
--- a/src/commands/CmdUnique.cpp
+++ b/src/commands/CmdUnique.cpp
@@ -25,7 +25,6 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 #include <cmake.h>
-#include <iostream>
 #include <string>
 #include <set>
 #include <algorithm>
@@ -88,7 +87,7 @@ int CmdUnique::execute (std::string& output)
 
   // Generate list of unique values.
   for (auto& value : values)
-    std::cout << value << "\n";
+    output += value + "\n";
 
   context.headers.clear ();
   return 0;
diff --git a/src/commands/Command.cpp b/src/commands/Command.cpp
index 1b857d34b..4b2baa739 100644
--- a/src/commands/Command.cpp
+++ b/src/commands/Command.cpp
@@ -312,7 +312,6 @@ Command::Category Command::category () const
 //   rc.confirmation
 //   this->_read_only
 bool Command::permission (
-  const Task& task,
   const std::string& question,
   unsigned int quantity)
 {
diff --git a/src/commands/Command.h b/src/commands/Command.h
index 70c3cb7b9..39bbe7468 100644
--- a/src/commands/Command.h
+++ b/src/commands/Command.h
@@ -71,7 +71,7 @@ public:
   virtual int execute (std::string&) = 0;
 
 protected:
-  bool permission (const Task&, const std::string&, unsigned int);
+  bool permission (const std::string&, unsigned int);
   static const std::map <Command::Category, std::string> categoryNames;
 
 protected: