I know that if you have some alias with the name
cp, you can bypass it using
Is this unix syntax? Are there any other uses of this syntax?
It's a feature of the shell and seems to be common to both the Bourne shell family (sh, ksh, bash, zsh) and the C shell family (csh, tcsh). It's based on character escaping. By escaping the first character (actually you can escape any character) it prevents alias expansion from being performed.
Escaping is used a lot. For just a very brief introduction to a small part of the usefulness of escaping, see the Quoting section in