Feature

- Added a 'uuids' command that parallels the 'ids' command.  This allows
  task UUIDs to be selected if the task is not pending.
- Updated documentation.

ChangeLog

@@ -6,7 +6,8 @@
 # Untracked Features, biggest first.
  + autoconf eliminated.
  + New 'ids' command that returns a filtered set of task ID numbers, instead
-   of the actual tasks.  For advanced pipeline use.
+   of the actual tasks.  Similarly there is a 'uuids' commands.  For advanced
+   pipeline use.
  + Now supplements the command line with data read from standard input, which
    allows commands like:  echo 'add Pay the bills' | task
  + Corrected sorting to use std::stable_sort instead of std::sort, which is not
@@ -38,6 +39,7 @@
  + The configuration variable 'json.array' determines whether 'query' command
    output is enclosed by '[...]'.
  + The duration 'm' is now interpreted as 'months', not 'minutes'.
+ 
 
 # Tracked Features, sorted by ID.
  + Added feature #278, which provides a more consistent command line grammar.

NEWS

@@ -2,7 +2,8 @@
 New Features in taskwarrior 2.0.0
 
   - New 'ids' command that returns a filtered set of task ID numbers, instead
-    of the actual tasks.  For advanced pipeline use.
+    of the actual tasks.  Similarly, there is a 'uuids' command.  For advanced
+    pipeline use.
   - Now supplements the command line with data read from standard input, which
     allows commands like:  echo 'add Pay the bills' | task
   - Attribute modifiers may be prefixed with '~' to return the opposite of a

doc/man/task.1.in

@@ -177,6 +177,17 @@ to achieve this:
 This example first gets the IDs for the project:Home filter, then sets
 the priority to H for each of those tasks.
 
+.TP
+.B task <filter> uuids
+Applies the filter then extracts only the task UUIDs and presents them as
+a comma-separated list.  This is useful as input to a task command, to achieve
+this:
+
+	task $(task project:Home status:completed uuids) modify status:pending
+
+This example first gets the UUIDs for the project:Home and status:completed
+filter, then makes each of those tasks pending again.
+
 .TP
 .B task <filter> information
 Shows all data and metadata for the specified tasks.

src/commands/CmdIDs.cpp

@@ -25,13 +25,13 @@
 //
 ////////////////////////////////////////////////////////////////////////////////
 
-
 #define L10N                                           // Localization complete.
 
 #include <sstream>
 #include <algorithm>
 #include <Context.h>
 #include <main.h>
+#include <text.h>
 #include <util.h>
 #include <i18n.h>
 #include <CmdIDs.h>
@@ -139,3 +139,32 @@ int CmdZshCompletionIds::execute (std::string& output)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+CmdUUIDs::CmdUUIDs ()
+{
+  _keyword     = "uuids";
+  _usage       = "task <filter> uuids";
+  _description = STRING_CMD_UUIDS_USAGE;
+  _read_only   = true;
+  _displays_id = false;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+int CmdUUIDs::execute (std::string& output)
+{
+  // Apply filter.
+  handleRecurrence ();
+  std::vector <Task> filtered;
+  filter (filtered);
+  context.tdb2.commit ();
+
+  std::vector <std::string> uuids;
+  std::vector <Task>::iterator task;
+  for (task = filtered.begin (); task != filtered.end (); ++task)
+    uuids.push_back (task->get ("uuid"));
+
+  join (output, ",", uuids);
+  output += "\n";
+  return 0;
+}
+
+////////////////////////////////////////////////////////////////////////////////

src/commands/CmdIDs.h

@@ -53,5 +53,12 @@ public:
   int execute (std::string&);
 };
 
+class CmdUUIDs : public Command
+{
+public:
+  CmdUUIDs ();
+  int execute (std::string&);
+};
+
 #endif
 ////////////////////////////////////////////////////////////////////////////////

src/commands/Command.cpp

@@ -156,6 +156,7 @@ void Command::factory (std::map <std::string, Command*>& all)
   c = new CmdTimesheet ();          all[c->keyword ()] = c;
   c = new CmdUndo ();               all[c->keyword ()] = c;
   c = new CmdUrgency ();            all[c->keyword ()] = c;
+  c = new CmdUUIDs ();              all[c->keyword ()] = c;
   c = new CmdVersion ();            all[c->keyword ()] = c;
   c = new CmdZshCommands ();        all[c->keyword ()] = c;
   c = new CmdZshCompletionIds ();   all[c->keyword ()] = c;

src/en-US.h

@@ -209,6 +209,7 @@
 #define STRING_CMD_IDS_USAGE_RANGE   "Shows the IDs of matching tasks, as a range"
 #define STRING_CMD_IDS_USAGE_LIST    "Shows only the IDs of matching tasks, in the form of a list"
 #define STRING_CMD_IDS_USAGE_ZSH     "Shows the IDs and descriptions of matching tasks"
+#define STRING_CMD_UUIDS_USAGE       "Shows the UUIDs of matching tasks"
 #define STRING_CMD_EXPORT_USAGE      "Exports tasks in JSON format"
 #define STRING_CMD_INFO_USAGE        "Shows all data and metadata"
 #define STRING_CMD_INFO_BLOCKED      "This task blocked by"