getgroups(2) manual page
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getgroups, setgroups - get or set supplementary group access list
IDs
#include <unistd.h>
int getgroups(int gidsetsize, gid_t *grouplist);
int setgroups(int ngroups, const gid_t *grouplist);
Async-Signal-Safe
getgroups() gets the current supplemental group access list
of the calling process and stores the result in the array of group ID
s
specified by grouplist. This array has gidsetsize entries and must be large
enough to contain the entire list. This list cannot be greater 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.
setgroups() sets the supplementary group access list of the
calling process from the array of group ID
s specified by grouplist. The
number of entries is specified by ngroups and can not be greater than NGROUPS_MAX.
This function may be invoked only by the super-user.
Upon successful
completion, getgroups() returns the number of supplementary group ID
s set
for the calling process and setgroups() returns the value 0. Otherwise,
a value of -1 is returned and errno is set to indicate the error.
getgroups()
will fail if:
- EINVAL
- The value of gidsetsize is non-zero and less than
the number of supplementary group ID
s set for the calling process.
setgroups()
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.
Either
call will fail if:
- EFAULT
- A referenced part of the array pointed to by
grouplist is an illegal address.
groups(1)
, chown(2)
, getuid(2)
,
setuid(2)
, getgrnam(3C)
, initgroups(3C)
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