Technical Reference: Base Operating System and Extensions, Volume 2

setgid, setrgid, setegid, setregid, or setgidx Subroutine

Purpose

Sets the process group IDs.

Library

Standard C Library (libc.a)

Syntax

#include <unistd.h>

int setgid (GID)
gid_t  GID;

int setrgid (RGID)
gid_t  RGID;

int setegid (EGID) gid_t EGID;

int setregid (RGID, EGID)
gid_t RGID;
gid_t EGID;

#include <unistd.h>
#include <sys/id.h>

int setgidx ( which, GID )
int which;
gid_t GID;

Description

The setgid, setrgid, setegid, setregid, and setgidx subroutines set the process group IDs of the calling process. The following semantics are supported:

setgid	If the effective user ID of the process is the root user, the process's real, effective, and saved group IDs are set to the value of the GID parameter. Otherwise, the process effective group ID is reset if the GID parameter is equal to either the current real or saved group IDs, or one of its supplementary group IDs. Supplementary group IDs of the calling process are not changed.
setegid	The process effective group ID is reset if one of the following conditions is met: The EGID parameter is equal to either the current real or saved group IDs. The EGID parameter is equal to one of its supplementary group IDs. The effective user ID of the process is the root user.
setrgid	The EPERM error code is always returned.
setregid	The RGID and EGID parameters can have one of the following relationships: RGID != EGID If the EGID parameter is equal to either the process's real or saved group IDs, the process effective group ID is set to the EGID parameter. Otherwise, the EPERM error code is returned. RGID == EGID If the effective user ID of the process is the root user, the process's real and effective group IDs are set to the EGID parameter. If the EGID parameter is equal to the process's real or saved group IDs, the process effective group ID is set to EGID. Otherwise, the EPERM error code is returned.
setgidx	The which parameter can have one of the following values: ID_EFFECTIVE GID must be either the real or saved GID or one of the values in the concurrent group set. The effective group ID for the current process will be set to GID. ID_EFFECTIVE\|ID_REAL Invoker must have appropriate privilege. The real and effective group ID for the current process will be set to GID. ID_EFFECTIVE\|ID_REAL\|ID_SAVED Invoker must have appropriate privilege. The real, effective and saved group ID for the current process will be set to GID.

The setegid, setrgid, setregid, and setgidx subroutines are thread-safe.

The operating system does not support setuid (setuid, setruid, seteuid, setreuid or setuidx Subroutine) or setgid shell scripts.

These subroutines are part of Base Operating System (BOS) Runtime.

Parameters

GID	Specifies the value of the group ID to set.
RGID	Specifies the value of the real group ID to set.
EGID	Specifies the value of the effective group ID to set.
which	Specifies which group ID values to set.

Return Values

0	Indicates that the subroutine was successful.
-1	Indicates the subroutine failed. The errno global variable is set to indicate the error.

Error Codes

If the setgid, setegid, or setgidx subroutine fails, one or more of the following are returned:

EPERM	Indicates the process does not have appropriate privileges and the GID or EGID parameter is not equal to either the real or saved group IDs of the process.
EINVAL	Indicates the value of the GID, EGID or which parameter is invalid.

Related Information

The getgid subroutine, getgroups subroutine, setgroups (setgroups Subroutine) subroutine, setuid (setuid, setruid, seteuid, setreuid or setuidx Subroutine) subroutine.

The setgroups command.

List of Security and Auditing Subroutines, Subroutines Overview in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.