NAME

setgid — set-group-ID

SYNOPSIS

#include <unistd.h>

int setgid(gid_t gid);


DESCRIPTION

If the process has appropriate privileges, setgid() shall set the real group ID, effective group ID, and the saved set-group-ID of the calling process to gid.

If the process does not have appropriate privileges, but gid is equal to the real group ID or the saved set-group-ID, setgid() shall set the effective group ID to gid; the real group ID and saved set-group-ID shall remain unchanged.

The setgid() function shall not affect the supplementary group list in any way.

Any supplementary group IDs of the calling process shall remain unchanged.

RETURN VALUE

Upon successful completion, 0 is returned. Otherwise, -1 shall be returned and errno set to indicate the error.

ERRORS

The setgid() function shall fail if:

[EINVAL]

The value of the gid argument is invalid and is not supported by the implementation.

[EPERM]

The process does not have appropriate privileges and gid does not match the real group ID or the saved set-group-ID.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

Refer to the RATIONALE section in setuid.

FUTURE DIRECTIONS

None.

SEE ALSO

exec, getegid, geteuid, getgid, getresgid, getresuid, getuid, setegid, seteuid, setregid, setresgid, setresuid, setreuid, setuid

XBD <sys/types.h>, <unistd.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

In the SYNOPSIS, the optional include of the <sys/types.h> header is removed.

The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:

• The requirement to include <sys/types.h> has been removed. Although <sys/types.h> was required for conforming implementations of previous POSIX specifications, it was not required for UNIX applications.

• Functionality associated with _POSIX_SAVED_IDS is now mandated. This is a FIPS requirement.

The following changes were made to align with the IEEE P1003.1a draft standard:

• The effects of setgid() in processes without appropriate privileges are changed.

• A requirement that the supplementary group list is not affected is added.

Issue 8

Austin Group Defect 1344 is applied, adding getresgid(), getresuid(), setresgid(), and setresuid() to SEE ALSO.