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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