On 11/03/2015 01:09 PM, Dennis Williamson wrote: > On Nov 3, 2015 12:47 PM, "Julio C. Neves" <julio.ne...@gmail.com> wrote: >> >> Thanks Dennis, >> I know that you are rigth, but "paste -d"" odd even" and "paste -d "" odd > even" are not the same? The diference is only a space between the option > and its parameter.
They are indeed not the same. In long option form, you have: paste -d "" odd even == paste --delimiters="" odd even == paste --delimiters= odd even == paste --delimiters "" odd even while: paste -d"" odd even == paste -d odd even == paste --delimiters=odd even == paste --delimiters odd even Remember, the shell strips quotes before it hands arguments to paste. Thus, paste is receiving, as argv, ["paste", "-d", "", "odd", "even"] for the first group, and ["paste", "-d", "odd", "even"] for the second group. There is NO way for any program using getopt() or getopt_long() to know if the user spelled '-d""' vs. '"-d"' vs. '-d', or any other myriad of patterns where the quotes are stripped. The ONLY way to pass an empty string argument to a short option is to do it as a separate argument, because the quotes are already stripped by the time argv is formed. Thus, the space is essential. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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