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30.\"     @(#)initgroups.3	8.1 (Berkeley) 6/4/93
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32.Dd August 10, 2002
33.Dt INITGROUPS 3
34.Os
35.Sh NAME
36.Nm initgroups
37.Nd initialize supplementary group IDs
38.Sh LIBRARY
39.Lb libc
40.Sh SYNOPSIS
41.In unistd.h
42.Ft int
43.Fn initgroups "const char *name" "gid_t basegid"
44.Sh DESCRIPTION
45The
46.Fn initgroups
47function
48uses the
49.Xr getgrouplist 3
50function to calculate the supplementary group IDs for the user
51specified in
52.Fa name .
53This group list is then set up for the current process using
54.Xr setgroups 2 .
55The
56.Fa basegid
57is automatically included in the group list.
58Typically this value is given as
59the group number from the password file.
60.Pp
61If the groups database lists more than
62.Ev NGROUPS
63groups for
64.Fa name
65(including one for
66.Fa basegid ) ,
67the later groups are ignored.
68.Sh RETURN VALUES
69The
70.Fn initgroups
71function
72returns \-1 if it was not invoked by the super-user.
73.Sh SEE ALSO
74.Xr setgroups 2 ,
75.Xr getgrouplist 3
76.Sh HISTORY
77The
78.Fn initgroups
79function appeared in
80.Bx 4.2 .
81.Sh BUGS
82The
83.Fn getgrouplist
84function called by
85.Fn initgroups
86uses the routines based on
87.Xr getgrent 3 .
88If the invoking program uses any of these routines,
89the group structure will
90be overwritten in the call to
91.Fn initgroups .
92