getgroups(2)




NAME

     getgroups, setgroups - get or set supplementary group access
     list IDs


SYNOPSIS

     #include <unistd.h>

     int getgroups(int gidsetsize, gid_t *grouplist);

     int setgroups(int ngroups, const gid_t *grouplist);


DESCRIPTION

     The getgroups() function gets the current supplemental group
     access  list of the calling process and stores the result in
     the array of group IDs specified by  grouplist.  This  array
     has  gidsetsize  entries and must be large enough to contain
     the  entire  list.  This  list   cannot   be   larger   than
     NGROUPS_MAX. If gidsetsize equals 0, getgroups() will return
     the number of groups to which the  calling  process  belongs
     without modifying the array pointed to by grouplist.

     The setgroups() function sets the supplementary group access
     list  of  the  calling  process  from the array of group IDs
     specified by grouplist. The number of entries  is  specified
     by ngroups and can not be greater than NGROUPS_MAX.


RETURN VALUES

     Upon successful completion, getgroups() returns  the  number
     of  supplementary  group IDs set for the calling process and
     setgroups() returns 0. Otherwise, -1 is returned  and  errno
     is set to indicate the error.


ERRORS

     The getgroups() and setgroups() functions will fail if:

     EFAULT
           A referenced part of the array pointed to by grouplist
           is an illegal address.

     The getgroups() function will fail if:

     EINVAL
           The value of gidsetsize is non-zero and less than  the
           number  of supplementary group IDs set for the calling
           process.

     The setgroups() function will fail if:

     EINVAL
           The value of ngroups is greater than NGROUPS_MAX.

     EPERM The effective user  of  the  calling  process  is  not
           super-user.


USAGE

     Use  of  the   setgroups()   function   requires   superuser
     privileges.


ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | Async-Signal-Safe           |
    |_____________________________|_____________________________|


SEE ALSO

     groups(1),  chown(2),  getuid(2),  setuid(2),  getgrnam(3C),
     initgroups(3C), attributes(5)


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