Here's a video by MNSweet demonstrating rotational direction detection:
Rather than checking the NBT data (i.e. using {}), rotation can be tested for using the target selector arguments ry, rym, rx, and rxm, denoting the maximum and minimum view angle in the horizontal (east, south, etc.) and vertical (up, down) direction, respectively.
For example, to test for someone looking South (=0±22), use
testfor @a[ry=22,rym=-22]
To test for someone looking 45° upwards (±10) and to the northeast (=135±22)
testfor @a[ry=-113,rym=-157,rx=55,rxm=35]
See Commands wiki page for more information.
When using selectors, all of the arguments go between the same pair of square brackets and are separated by commas. What you wanted to do is probably this:
testfor @e[type=PrimedTnt,x=-272,y=58,z=-1844]
You're getting the error message because you've made [x=-272 y=58 z=-1844] an argument of its own, not part of the selector. As it happens, the second argument for testfor is NBT data. The correct syntax to specify NBT data would, as the answer above says, be {x:-272,y:58,z:-1844}.
HOWEVER no entity has an "x" int, a "y" int, and a "z" int in it's data. Although it's the correct syntax and won't cause an error, it will never match an entity. The correct tags for specifying location with the NBT argument would be this:
testfor @e[type=PrimedTnt] {Pos:[-271.5,58.5,-1843.5]}
The chances are you didn't want to do that though, as it'd test only for that very specific point in space and nothing else. The solution is the first command I gave, where all of the arguments are in the square brackets.
Best Answer
You should use
/executeto have the command executed from the player rather than the command block: