STYLE: remove unnecessary stdout, stderr /dev/null redirects

- no stderr redirect needed:
    * 'command -v'

- no stdout/stderr redirect needed:
    * 'rm -f'

STYLE: consistent spacing after redirects

tutorials/mesh/foamyHexMesh/mixerVessel/Allrun-pre

@@ -16,7 +16,7 @@ intersectSurfaces()
 }
 
 
-\rm -rf 0
+rm -rf 0
 
 
 # Run the surface preparation script
@@ -76,7 +76,7 @@ then
     runApplication reconstructParMesh -latestTime
 
     \cp -r $latestTime/polyMesh constant
-    \rm -rf $latestTime
+    rm -rf $latestTime
 fi