rust-lang/cargo — pull request #412 by ScriptDevil (2014-08-20 16:57:27+00:00)
Title: Print help message if cargo is invoked with no arguments

Most modern command line utilities print usage/help when invoked without any arguments.

cargo (prior to this patch) defaults to saying "no such subcommand" when invoked without arguments.
> $ cargo
> No such subcommand

With this patch, it will instead print the help message
> $ cargo
> Rust's package manager
>
> Usage:
> ...