Top two are wrong… Not a good thing. It's always the same badly written snippets that get copy-pasted across websites without anyone really understanding what it does (hence the copy/paste).

> alias servethis="python -c 'import SimpleHTTPServer; SimpleHTTPServer.test()'"

    python -m SimpleHTTPServer # python 3
    python -m http.server # Python 3

> extract () { /* useless stuff */ }

   tar xf