SETGID
Section: Linux Programmer's Manual (2)
Updated: 29 July 1994
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NAME
setgid - set group identity
SYNOPSIS
#include <unistd.h>
int setgid(gid_t gid)
DESCRIPTION
setgid
sets the effective group ID of the current process. If the caller is the
superuser, the real and saved group ID's are also set.
Under Linux,
setgid
is implemented like SYSV with SAVED_IDS.
This allows a setgid (other than root) program to drop all of it's group
privileges, do some un-privileged work, and then re-engage the original
effective group ID in a secure manner.
If the user is root or the program is setgid root, special care must be
taken. The
setgid
function checks the effective gid of the caller and if it is the superuser,
all process related group ID's are set to
gid.
After this has occurred, it is impossible for the program to regain root
privileges.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and
errno
is set appropriately.
ERRORS
- EPERM
-
The user is not the super-user, and
gid
does not match the effective or saved group ID of the calling process.
CONFORMING TO
System V
SEE ALSO
getgid(2), setregid(2), setegid(2)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- SEE ALSO
-
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