diff --git a/System/Posix/ARX/CLI.hs b/System/Posix/ARX/CLI.hs
--- a/System/Posix/ARX/CLI.hs
+++ b/System/Posix/ARX/CLI.hs
@@ -15,6 +15,7 @@
 import Data.Maybe
 import Data.Monoid
 import Data.Ord
+import Data.Semigroup
 import Data.Word
 import System.Environment
 import System.Exit (exitFailure)
@@ -43,11 +44,12 @@
       let apply i            =  interpret (SHDAT size) <$> inIOStream i
       mapM_ ((send out =<<) . apply) ins
     Right (Right tmpxArgs)  ->  do
-      let (sz, out, tars, env, (rm0, rm1), shared, cmd) = tmpxResolve tmpxArgs
+      let (sz, out, tars, env, tmpdir,
+           (rm0, rm1), shared, cmd) = tmpxResolve tmpxArgs
       case tmpxCheckStreams tars cmd of Nothing  -> return ()
                                         Just msg -> do die msg
       cmd'                  <-  openByteSource cmd
-      let tmpx               =  TMPX (SHDAT sz) cmd' env rm0 rm1 shared
+      let tmpx               =  TMPX (SHDAT sz) cmd' env tmpdir rm0 rm1 shared
       (badAr, goodAr)       <-  partitionEithers <$> mapM openArchive tars
       (badAr /= []) `when` do (((die .) .) . blockMessage)
                                 "The file magic of some archives:"
@@ -86,16 +88,17 @@
 {-| Apply defaulting and overrides appropriate to 'TMPX' programs.
  -}
 tmpxResolve                 ::  ( [Word], [IOStream], [IOStream],
-                                  [(Var, Val)], [(Bool, Bool)], [Bool],
-                                  [ByteSource]                          )
+                                  [(Var, Val)], [ByteString], [(Bool, Bool)],
+                                  [Bool], [ByteSource]              )
                             ->  ( Word, IOStream, [IOStream],
-                                  [(Var, Val)], (Bool, Bool), Bool,
+                                  [(Var, Val)], ByteString, (Bool, Bool), Bool,
                                   ByteSource                        )
-tmpxResolve (sizes, outs, tars, env, rms, shareds, cmds) =
-  (size, out, tars, env, rm, shared, cmd)
+tmpxResolve (sizes, outs, tars, env, dirs, rms, shareds, cmds) =
+  (size, out, tars, env, tmpdir, rm, shared, cmd)
  where
   size                       =  last (defaultBlock:sizes)
   out                        =  last (STDIO:outs)
+  tmpdir                     =  last ("/tmp":dirs)
   rm                         =  last ((True,True):rms)
   shared                     =  last (False:shareds)
   cmd                        =  last (defaultTask:cmds)
@@ -111,13 +114,14 @@
     | cmd == IOStream STDIO  =  One "as a command input"
     | otherwise              =  Zero
 
-tmpxOpen :: Word -> [(Var, Val)] -> (Bool, Bool, Bool) -> ByteSource -> IO TMPX
-tmpxOpen size env (rm0, rm1, rm2) cmd = do
+tmpxOpen :: Word -> [(Var, Val)] -> (Bool, Bool, Bool)
+         -> ByteString -> ByteSource -> IO TMPX
+tmpxOpen size env (rm0, rm1, rm2) tmpdir cmd = do
   text                      <-  case cmd of
     ByteString b            ->  return (LazyB.fromChunks [b])
     IOStream STDIO          ->  LazyB.getContents
     IOStream (Path b)       ->  LazyB.readFile (Char8.unpack b)
-  return (TMPX (SHDAT size) text env rm0 rm1 rm2)
+  return (TMPX (SHDAT size) text env tmpdir rm0 rm1 rm2)
 
 
 openByteSource              ::  ByteSource -> IO LazyB.ByteString
@@ -150,14 +154,15 @@
 
 
 data ZOM                     =  Zero | One !ByteString | Many ![ByteString]
+instance Semigroup ZOM where
+  Zero    <> x        =  x
+  x       <> Zero     =  x
+  One m   <> One m'   =  Many [m, m']
+  One m   <> Many ms  =  Many (mappend [m] ms)
+  Many ms <> One m    =  Many (mappend ms  [m])
+  Many ms <> Many ms' =  Many (mappend ms  ms')
 instance Monoid ZOM where
   mempty                     =  Zero
-  Zero    `mappend` x        =  x
-  x       `mappend` Zero     =  x
-  One m   `mappend` One m'   =  Many [m, m']
-  One m   `mappend` Many ms  =  Many (mappend [m] ms)
-  Many ms `mappend` One m    =  Many (mappend ms  [m])
-  Many ms `mappend` Many ms' =  Many (mappend ms  ms')
 
 streamsMessage filtered      =  case foldl' mappend Zero filtered of
   Many messages             ->  Just (template messages)
diff --git a/System/Posix/ARX/CLI/Options.hs b/System/Posix/ARX/CLI/Options.hs
--- a/System/Posix/ARX/CLI/Options.hs
+++ b/System/Posix/ARX/CLI/Options.hs
@@ -39,7 +39,7 @@
     f _ stuff                =  stuff
 
 tmpx :: ArgsParser ( [Word], [IOStream], [IOStream], [(Sh.Var, Sh.Val)],
-                     [(Bool, Bool)], [Bool], [ByteSource]                )
+                     [ByteString], [(Bool, Bool)], [Bool], [ByteSource] )
 tmpx                         =  do
   arg "tmpx"
   bars                      <-  (try . lookAhead) slashes
@@ -47,38 +47,41 @@
                  Nothing    ->  flags eof
                  Just bars  ->  do let eof_bars = () <$ arg bars <|> eof
                                    before <- flags eof_bars
-                                   cmd <- _7 (gather eof_bars)
+                                   cmd <- _8 (gather eof_bars)
                                    after <- flags eof
                                    return (before ++ (cmd:after))
  where
   flags                      =  manyTill flag
   gather = (ByteString . Char8.unwords <$>) . manyTill anyArg
   flag                       =  _1 blockSize <|> _2 outputFile <|> _3 ioStream
-                            <|> _4 env       <|> _5 rm         <|> _6 shared
-                            <|> _7 scriptToRun
-  _1 = ((,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing) . Just <$>)
-  _2 = ((Nothing,,Nothing,Nothing,Nothing,Nothing,Nothing) . Just <$>)
-  _3 = ((Nothing,Nothing,,Nothing,Nothing,Nothing,Nothing) . Just <$>)
-  _4 = ((Nothing,Nothing,Nothing,,Nothing,Nothing,Nothing) . Just <$>)
-  _5 = ((Nothing,Nothing,Nothing,Nothing,,Nothing,Nothing) . Just <$>)
-  _6 = ((Nothing,Nothing,Nothing,Nothing,Nothing,,Nothing) . Just <$>)
-  _7 = ((Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,) . Just <$>)
-  coalesce                   =  foldr f ([], [], [], [], [], [], [])
+                            <|> _4 env       <|> _5 tmpdir     <|> _6 rm
+                            <|> _7 shared    <|> _8 scriptToRun
+  _1 = ((,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing) . Just <$>)
+  _2 = ((Nothing,,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing) . Just <$>)
+  _3 = ((Nothing,Nothing,,Nothing,Nothing,Nothing,Nothing,Nothing) . Just <$>)
+  _4 = ((Nothing,Nothing,Nothing,,Nothing,Nothing,Nothing,Nothing) . Just <$>)
+  _5 = ((Nothing,Nothing,Nothing,Nothing,,Nothing,Nothing,Nothing) . Just <$>)
+  _6 = ((Nothing,Nothing,Nothing,Nothing,Nothing,,Nothing,Nothing) . Just <$>)
+  _7 = ((Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,,Nothing) . Just <$>)
+  _8 = ((Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,) . Just <$>)
+  coalesce                   =  foldr f ([], [], [], [], [], [], [], [])
    where
-    f (Just a, _, _, _, _, _, _)   (as, bs, cs, ds, es, fs, gs)
-                                =  (a:as, bs, cs, ds, es, fs, gs)
-    f (_, Just b, _, _, _, _, _)   (as, bs, cs, ds, es, fs, gs)
-                                =  (as, b:bs, cs, ds, es, fs, gs)
-    f (_, _, Just c, _, _, _, _)   (as, bs, cs, ds, es, fs, gs)
-                                =  (as, bs, c:cs, ds, es, fs, gs)
-    f (_, _, _, Just d, _, _, _)   (as, bs, cs, ds, es, fs, gs)
-                                =  (as, bs, cs, d:ds, es, fs, gs)
-    f (_, _, _, _, Just e, _, _)   (as, bs, cs, ds, es, fs, gs)
-                                =  (as, bs, cs, ds, e:es, fs, gs)
-    f (_, _, _, _, _, Just f, _)   (as, bs, cs, ds, es, fs, gs)
-                                =  (as, bs, cs, ds, es, f:fs, gs)
-    f (_, _, _, _, _, _, Just g)   (as, bs, cs, ds, es, fs, gs)
-                                =  (as, bs, cs, ds, es, fs, g:gs)
+    f (Just a, _, _, _, _, _, _, _)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (a:as, bs, cs, ds, es, fs, gs, hs)
+    f (_, Just b, _, _, _, _, _, _)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (as, b:bs, cs, ds, es, fs, gs, hs)
+    f (_, _, Just c, _, _, _, _, _)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (as, bs, c:cs, ds, es, fs, gs, hs)
+    f (_, _, _, Just d, _, _, _, _)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (as, bs, cs, d:ds, es, fs, gs, hs)
+    f (_, _, _, _, Just e, _, _, _)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (as, bs, cs, ds, e:es, fs, gs, hs)
+    f (_, _, _, _, _, Just f, _, _)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (as, bs, cs, ds, es, f:fs, gs, hs)
+    f (_, _, _, _, _, _, Just g, _)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (as, bs, cs, ds, es, fs, g:gs, hs)
+    f (_, _, _, _, _, _, _, Just h)   (as, bs, cs, ds, es, fs, gs, hs)
+                                =  (as, bs, cs, ds, es, fs, gs, h:hs)
     f _ stuff                   =  stuff
 
 blockSize                   ::  ArgsParser Word
@@ -98,6 +101,8 @@
 shared                      ::  ArgsParser Bool
 shared                       =  True <$ arg "--shared"
 
+tmpdir                      ::  ArgsParser ByteString
+tmpdir                       =  arg "--tmpdir" >> tokCL QualifiedPath
 
 rm                          ::  ArgsParser (Bool, Bool)
 rm  =   (True,  False) <$ arg "-rm0"  <|>  (False, True) <$ arg "-rm1"
diff --git a/System/Posix/ARX/Programs.hs b/System/Posix/ARX/Programs.hs
--- a/System/Posix/ARX/Programs.hs
+++ b/System/Posix/ARX/Programs.hs
@@ -57,12 +57,13 @@
  -}
 data TMPX = TMPX SHDAT LazyB.ByteString -- Code of task to run.
                        [(Sh.Var, Sh.Val)] -- Environment mapping.
+                       ByteString -- Place to put tmp dir.
                        Bool -- Destroy tmp if task runs successfully.
                        Bool -- Destroy tmp if task exits with an error code.
                        Bool -- Reuse tmp dir if available.
 instance ARX TMPX [(Tar, LazyB.ByteString)] where
-  interpret (TMPX encoder run env rm0 rm1 rm2) stuff = TMPXTools.render
-    (TMPXTools.Template rm0 rm1 rm2 env' run' archives)
+  interpret (TMPX encoder run env tmpdir rm0 rm1 rm2) stuff = TMPXTools.render
+    (TMPXTools.Template rm0 rm1 rm2 tmpdir env' run' archives)
    where
     archives                 =  mconcat (uncurry archive <$> stuff)
     archive tar bytes        =  mconcat
@@ -70,6 +71,7 @@
     flags TAR                =  "-x"
     flags TGZ                =  "-x -z"
     flags TBZ                =  "-x -j"
+    flags TXZ                =  "-x -J"
     run' = case run of ""   ->  ""
                        _    ->  shdat run
     env' = case env of _:_  ->  (shdat . unblz . Sh.render) env
diff --git a/System/Posix/ARX/TMPXTools.hs b/System/Posix/ARX/TMPXTools.hs
--- a/System/Posix/ARX/TMPXTools.hs
+++ b/System/Posix/ARX/TMPXTools.hs
@@ -22,12 +22,14 @@
 data Template = Template { rm0    :: Bool, {-^ Remove tmp on run success?    -}
                            rm1    :: Bool, {-^ Remove tmp on run error?      -}
                            shared :: Bool, {-^ Share directory across runs?  -}
+                           tmpdir :: ByteString,    {-^ Temp file location.  -}
                            env    :: Blaze.Builder, {-^ Stream for env text. -}
                            run    :: Blaze.Builder, {-^ Stream for run text. -}
                            dat    :: Blaze.Builder  {-^ Data text. -} }
 instance Show Template where
   show Template{..} =
-    "Template { rm0=" ++ tf rm0 ++ " rm1=" ++ tf rm1 ++
+    "Template { tmpdir=" ++ Bytes.unpack tmpdir
+              ++ " rm0=" ++ tf rm0 ++ " rm1=" ++ tf rm1 ++
               " shared=" ++ tf shared ++  " ... }"
    where
     tf True                  =  "true"
@@ -47,14 +49,15 @@
   flags                      =  mconcat [ "rm0=", tf rm0, " ; ",
                                           "rm1=", tf rm1, " ; ",
                                           "shared=", tf shared, " ; ",
-                                          "hash=", (hexStr . hash) dat, "\n" ]
+                                          "hash=", (hexStr . hash) dat, " ; ",
+                                          "tmpdir=", blaze tmpdir, "\n" ]
   hash                       =  abs . Data.Hashable.hash . Blaze.toByteString
   hexStr                     =  blaze . Bytes.pack . hex
   hex i = Numeric.showIntAtBase 16 Data.Char.intToDigit i ""
   blaze                      =  Blaze.fromByteString
   tf True                    =  "true"
   tf False                   =  "false"
-  a : b : c : d : e : [] = findChunks $(embedFile "./model-scripts/tmpx.sh")
+  a : b : c : d : e : f : [] = findChunks $(embedFile "./model-scripts/tmpx.sh")
 
 findChunks                  ::  ByteString -> [ByteString]
 findChunks                   =  coalesce . markHoles
diff --git a/System/Posix/ARX/Tar.hs b/System/Posix/ARX/Tar.hs
--- a/System/Posix/ARX/Tar.hs
+++ b/System/Posix/ARX/Tar.hs
@@ -9,7 +9,7 @@
 
 {-| Handled styles of Tar archive.
  -}
-data Tar                     =  TAR | TGZ | TBZ
+data Tar                     =  TAR | TBZ | TGZ | TXZ
 deriving instance Eq Tar
 deriving instance Ord Tar
 deriving instance Show Tar
@@ -21,6 +21,7 @@
 magic b | bzMagic b          =  Just TBZ
         | gzMagic b          =  Just TGZ
         | tarMagic b         =  Just TAR
+        | xzMagic b          =  Just TXZ
         | otherwise          =  Nothing
 
 bzMagic                      =  (== "BZh")      . take 3
@@ -29,3 +30,6 @@
 
 tarMagic                     =  (== "ustar")    . take 5 . drop 257
 
+xzMagic                      =  (== xzBytes)    . take 6
+ where
+  xzBytes                    = '\xFD' `cons` "7zXZ\0"
diff --git a/arx.cabal b/arx.cabal
--- a/arx.cabal
+++ b/arx.cabal
@@ -1,5 +1,5 @@
 name                          : arx
-version                       : 0.2.3
+version                       : 0.3.0
 category                      : Text
 license                       : BSD3
 license-file                  : LICENSE
@@ -85,8 +85,8 @@
                                 System.Posix.ARX.HEREDat
                                 System.Posix.ARX.Programs
                                 System.Posix.ARX.Sh
-                                System.Posix.ARX.Tar
                                 System.Posix.ARX.TMPXTools
+                                System.Posix.ARX.Tar
   extensions                  : FlexibleInstances
                                 FunctionalDependencies
                                 MultiParamTypeClasses
@@ -119,4 +119,13 @@
                                 OverloadedStrings
                                 StandaloneDeriving
                                 TupleSections
+  other-modules:                System.Posix.ARX
+                                System.Posix.ARX.CLI
+                                System.Posix.ARX.CLI.CLTokens
+                                System.Posix.ARX.CLI.Options
+                                System.Posix.ARX.HEREDat
+                                System.Posix.ARX.Programs
+                                System.Posix.ARX.Sh
+                                System.Posix.ARX.TMPXTools
+                                System.Posix.ARX.Tar
 
diff --git a/model-scripts/tmpx.sh b/model-scripts/tmpx.sh
--- a/model-scripts/tmpx.sh
+++ b/model-scripts/tmpx.sh
@@ -2,7 +2,7 @@
 set -e -u
 unset rm_ dir
 tmp=true ; run=true
-rm0=true ; rm1=true ; shared=false ; hash="" # To be set by tool.
+tmpdir= ; rm0=true ; rm1=true ; shared=false ; hash="" # To be set by tool.
 token=`date -u +%FT%TZ | tr -d :-`-`hexdump -n4 -e '"%08x"' </dev/urandom`
 opts() {
   cmd="$1" ; shift
@@ -39,9 +39,9 @@
     if $shared
     then
       rm_=false
-      dir=/tmp/tmpx-"$hash"
+      dir="$tmpdir"/tmpx-"$hash"
     else
-      dir=/tmp/tmpx-"$token"
+      dir="$tmpdir"/tmpx-"$token"
     fi
     : ${rm_:=true}
     if $rm_