Editing Group identifier (section)

=== Special values ===

* 0: The [[superuser]] normally has a GID of zero (0).
* −1: The value <code>(gid_t) -1</code> is reserved by POSIX to identify an omitted argument.<ref>{{Cite web|title=chown|url=https://pubs.opengroup.org/onlinepubs/009695399/functions/chown.html|access-date=2021-12-06|website=pubs.opengroup.org}}</ref>
* 65,534: The Linux kernel defaults to 2<sup>16</sup>−2 = 65,534 (which many Linux distributions map to the group name "nogroup") when a 32-bit GID does not fit into the return value of a 16-bit system call.<ref>{{Cite web|title=Namespaces in operation, part 5: User namespaces [LWN.net]|url=https://lwn.net/Articles/532593/|access-date=2021-12-06|website=lwn.net}}</ref> The value is also returned by [[idmapd]] if a group name in an incoming [[NFSv4]] packet does not match any known group on the system.