setgroups(2)

1getgroups(2)                     System Calls                     getgroups(2)
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NAME

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

9       #include <unistd.h>
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11       int getgroups(int gidsetsize, gid_t *grouplist);
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14       int setgroups(int ngroups, const gid_t *grouplist);
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DESCRIPTION

18       The  getgroups()  function  gets  the current supplemental group access
19       list of the calling process and stores the result in the array of group
20       IDs  specified by grouplist. This array has gidsetsize entries and must
21       be large enough to contain the entire list. This list cannot be  larger
22       than  NGROUPS_UMAX. If gidsetsize equals 0, getgroups() will return the
23       number of groups to which the calling process belongs without modifying
24       the array pointed to by grouplist.
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27       The  setgroups()  function  sets the supplementary group access list of
28       the calling process from the array of group IDs specified by grouplist.
29       The  number  of  entries is specified by ngroups and can not be greater
30       than NGROUPS_MAX.
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RETURN VALUES

33       Upon successful completion, getgroups() returns the number  of  supple‐
34       mentary  group  IDs set for the calling process and setgroups() returns
35       0. Otherwise, −1 is returned and errno is set to indicate the error.
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ERRORS

38       The getgroups() and setgroups() functions will fail if:
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40       EFAULT    A referenced part of the array pointed to by grouplist is  an
41                 illegal address.
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45       The getgroups() function will fail if:
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47       EINVAL    The  value of gidsetsize is non-zero and less than the number
48                 of supplementary group IDs set for the calling process.
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52       The setgroups() function will fail if:
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54       EINVAL    The value of ngroups is greater than {NGROUPS_MAX}.
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57       EPERM     The {PRIV_PROC_SETID} privilege is not asserted in the effec‐
58                 tive set of the calling process.
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USAGE

62       Use  of  the setgroups() function requires the {PRIV_PROC_SETID} privi‐
63       lege.
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ATTRIBUTES

66       See attributes(5) for descriptions of the following attributes:
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71       ┌─────────────────────────────┬─────────────────────────────┐
72       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
73       ├─────────────────────────────┼─────────────────────────────┤
74       │Interface Stability          │getgroups() is Standard.     │
75       ├─────────────────────────────┼─────────────────────────────┤
76       │MT-Level                     │Async-Signal-Safe            │
77       └─────────────────────────────┴─────────────────────────────┘
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