SETGID(2) manual page
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setgid - set group identity
#include
<sys/types.h>
#include <unistd.h>
int setgid(gid_t gid);
setgid() sets the effective
group ID of the calling process. If the caller is the superuser, the real
GID and saved set-group-ID are also set.
Under Linux, setgid() is implemented
like the POSIX version with the _POSIX_SAVED_IDS feature. This allows a
set-group-ID program that is not set-user-ID-root to drop all of its group privileges,
do some un-privileged work, and then reengage the original effective group
ID in a secure manner.
On success, zero is returned. On error,
-1 is returned, and errno is set appropriately.
- EINVAL
- The group ID
specified in gid is not valid in this user namespace.
- EPERM
- The calling
process is not privileged (does not have the CAP_SETGID capability), and
gid does not match the real group ID or saved set-group-ID of the calling
process.
SVr4, POSIX.1-2001.
The original Linux setgid()
system call supported only 16-bit group IDs. Subsequently, Linux 2.4 added
setgid32() supporting 32-bit IDs. The glibc setgid() wrapper function transparently
deals with the variation across kernel versions.
getgid(2)
, setegid(2)
,
setregid(2)
, capabilities(7)
, credentials(7)
, user_namespaces(7)
This
page is part of release 3.78 of the Linux man-pages project. A description
of the project, information about reporting bugs, and the latest version
of this page, can be found at http://www.kernel.org/doc/man-pages/.
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