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Technical Reference: Base Operating System and Extensions , Volume 2

setgid, setrgid, setegid, or setregid 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;

Description

The setgid, setrgid, setegid, and setregid 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.

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

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.

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 either the setgid or setegid 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 or EGID parameter is invalid.

Implementation Specifics

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

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

Related Information

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

The setgroups command.

List of Security and Auditing Subroutines, Subroutines Overview in AIX 5L Version 5.1 General Programming Concepts: Writing and Debugging Programs.

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