I just installed line_profiler using pip on Ubuntu. I closed and reopened the terminal, cd'd into the directory with my file to time, and ran kernprof. Bash is telling me it can't find kernprof. Coincidentally, I just did the exact same procedure on windows and it worked fine.
EDIT: So pip didn't actually install it, or put kernprof in the wrong directory. Downloading the tarball from pypi and running setup works.