[CentOS] claiming unsused space back

[Warren Young]

On Jul 31, 2017, at 4:27 PM, Leroy Tennison <leroy at datavoiceint.com> wrote:
> 
> some commands (or command options) are only supported on later releases, the man pages don't say this.

You only run into that problem when trying to use man pages from one system but then run commands on a very different system.  The man pages actually installed on the system you’re running the command on lists only those options that are supported by that version of the command.

> Does anyone know of a source of information listing the command, option and version it is implemented in?

The closest thing I’m aware of is the man page collection at unix.com:

    http://www.unix.com/man-page/linux/1/ls/

They don’t have man pages for absolutely every version of Linux — that would require hundreds of sets! — and it only includes commands in the base system, not those for add-on packages.

In this particular case, I suspect the problem is that you haven’t got the libguestfs-tools-c package installed, which is what owns the virt-sparsify command.  And I found that out with one Google search and one “yum search” command.

With that package installed, now you can say “man virt-sparsify” to find out what the CentOS 7 version of that command understands.