Use thirdparty GNU style flag packages

[yegle]

The flag package in golang doesn't support combination of short flags.

e.g. in GNU style, -help means -h -e -l -p, and -n1 means -n=1.

But in Go -help means --help, and -n1 means --n1. Without a proper GNU style flag parser, there's no easy way to support things like tail -n10.

Here's a short list of packages I googled that do GNU style flag parsing:

• https://github.com/ogier/pflag
• https://launchpad.net/gnuflag
• https://github.com/alecthomas/kingpin

I'll be happy to provide some PR if any of the packages are accepted as replacement.

[yegle]

Also thirdparty package candidate: https://code.google.com/p/getopt/

[mattn]

+1

[mattn]

I do always

$ ls -la
$ rm -rf ...

etc...

[yegle]

I've played and tested https://github.com/ogier/pflag This is a good drop-in replacement to Go's flag package (e.g. just change the import path and everything works fine). But it lacks some feature if we want to use it to simulate all coreutils flag behaviour.

One notable things that pflag can't do is the optional argument for non-bool flags. The example is ls --color which means ls --color=always. This is a flag.String in pflag, but you'll have to supply a value for such a flag.

I've reported this issue ogier/pflag#16 but I don't think there's an easy fix for the problem.

Moving on to test the other packages.

[abramisola]

Keeping in the spirit of the project, we won't be using third party services for any of the files at this point.