Shell-quoting, à la Perl's quotemeta function.

One idiom when writing simple shell tools in Rust (or Perl or whatever) is to spit out a shell script or shell fragment for later perusal and/or piping directly into a shell. However, a simple println! generates an incorrect and potentially insecure script if the filename happens to contain shell metacharacters. This includes the not exactly uncommon space character. Perl includes a quotemeta function which usually does the job. Let's do the job properly!

(Actually, you can't even println! a plain Path/PathBuf because they don't implement Display.)

This crate provides a function which quotes and escapes filenames (or other data) such that it can be interpolated. For example:

``` use quotemeta::quotemeta;

fn main() { for path in std::env::args_os().skip(1) { println!("cat {}", quotemeta(path)); } } ```

This will work even if the filename contains a carriage return, or is invalid UTF-8.