I'm trying to view changes for single file that is unstaged.
first i use
git diff AndroidManifest.xml
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
old mode 100755
new mode 100644
Most probably, the contents of this file haven't changed, only the executable bit has been cleared. Try actually changing the file by, say, appending an empty line to it, and see what
git diff outputs.
Apart from file contents, Git also records the state of the executable bit for each file. It makes sense on Linux systems if you want scripts to be executable right after checkout. See also the following two related questions: