Fix typo in tutorial.

llvm-svn: 238885

clang/docs/LibASTMatchersTutorial.rst

@@ -169,7 +169,7 @@ You should now be able to run the syntax checker, which is located in
 
 .. code-block:: console
 
-      cat "int main() { return 0; }" > test.cpp
+      echo "int main() { return 0; }" > test.cpp
       bin/loop-convert test.cpp --
 
 Note the two dashes after we specify the source file. The additional