getgroups.2 (2010 09)

g
getgroups(2) getgroups(2)
NAME
getgroups - get group access list
SYNOPSIS
#include <unistd.h>
int getgroups(int ngroups, gid_t gidset[ ]);
DESCRIPTION
getgroups() gets the current group access list of the user process and stores it in the array gidset .
The parameter ngroups indicates the number of entries which may be placed in gidset .
As a special case, if the ngroups argument is zero,
getgroups() returns the number of group entries
for the process. In this case, the array pointed to by the gidset argument is not modified.
EXAMPLES
The following call to
getgroups() (see getgroups (2)) retrieves the group access list of the calling pro-
cess and stores the group ids in array mygidset:
int ngroups, ngroups_max;
gid_t *mygidset;
ngroups_max = (int) sysconf(_SC_NGROUPS_MAX);
mygidset = (gid_t *) malloc(sizeof(gid_t) * ngroups_max);
ngroups = getgroups(ngroups_max, mygidset);
RETURN VALUE
If successful, getgroups() returns a non-negative value indicating the number of elements returned in
gidset . If an error occurs, a value of −1 is returned and errno is set to indicate the type of error.
ERRORS
getgroups() fails if any of the following conditions are encountered:
[EFAULT] gidset specifies an invalid address. The reliable detection of this error is implementation
dependent.
[EINVAL] The argument ngroups is not zero and is less than the number of groups in the current
group access list of the process.
AUTHOR
getgroups() was developed by HP and the University of California, Berkeley.
SEE ALSO
setgroups(2), sysconf(2), initgroups(3C).
STANDARDS CONFORMANCE
getgroups(): AES, SVID3, XPG3, XPG4, FIPS 151-2, POSIX.1
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1