man3/initgroups.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  29 .\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
  30 .\" Modified 2004-10-10 by aeb
  31 .\"
  32 .TH INITGROUPS 3  2015-03-29 "GNU" "Linux Programmer's Manual"
  33 .SH NAME
  34 initgroups \- initialize the supplementary group access list
  35 .SH SYNOPSIS
  36 .nf
  37 .B #include <sys/types.h>
  38 .B #include <grp.h>
  39 .sp
  40 .BI "int initgroups(const char *" user ", gid_t " group );
  41 .fi
  42 .sp
  43 .in -4n
  44 Feature Test Macro Requirements for glibc (see
  45 .BR feature_test_macros (7)):
  46 .in
  47 .sp
  48 .BR initgroups ():
  49 _BSD_SOURCE
  50 .SH DESCRIPTION
  51 The
  52 .BR initgroups ()
  53 function initializes the group access list by
  54 reading the group database
  55 .I /etc/group
  56 and using all groups of
  57 which
  58 .I user
  59 is a member.
  60 The additional group
  61 .I group
  62 is
  63 also added to the list.
  64
  65 The
  66 .I user
  67 argument must be non-NULL.
  68 .SH RETURN VALUE
  69 The
  70 .BR initgroups ()
  71 function returns 0 on success.
  72 On error, \-1 is returned, and
  73 .I errno
  74 is set appropriately.
  75 .SH ERRORS
  76 .TP
  77 .B ENOMEM
  78 Insufficient memory to allocate group information structure.
  79 .TP
  80 .B EPERM
  81 The calling process has insufficient privilege.
  82 See the underlying system call
  83 .BR setgroups (2).
  84 .SH FILES
  85 .nf
  86 \fI/etc/group\fP                group database file
  87 .fi
  88 .SH ATTRIBUTES
  89 For an explanation of the terms used in this section, see
  90 .BR attributes (7).
  91 .TS
  92 allbox;
  93 lb lb lb
  94 l l l.
  95 Interface       Attribute       Value
  96 T{
  97 .BR initgroups ()
  98 T}      Thread safety   MT-Safe locale
  99 .TE
 100
 101 .SH CONFORMING TO
 102 SVr4, 4.3BSD.
 103 .SH SEE ALSO
 104 .BR getgroups (2),
 105 .BR setgroups (2),
 106 .BR credentials (7)