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getgroups(2) [ultrix man page]

getgroups(2)							System Calls Manual						      getgroups(2)

Name
       getgroups - get group access list

Syntax
       #include <sys/types.h>
       #include <unistd.h>

       int getgroups(gidsetsize, grouplist)
       int gidsetsize;
       int grouplist[];

Description
       The  call  gets	the  current  group access list of the user process and stores it in the array of int grouplist.  The gidsetsize parameter
       indicates the number of entries that can be placed in grouplist.

Return Values
       Upon success, the call returns the number of groups as the value of the function.  No more than NGROUPS, as defined in  <sys/param.h>,  are
       returned.

       A value of -1 indicates that an error occurred, and the error code is stored in the global variable, errno.

Diagnostics
       The call fails under the following conditions:

       [EINVAL]       The gidsetsize argument is smaller than the number of groups in the group set.

       [EFAULT]       The grouplist argument specifies invalid addresses.

Environment
   POSIX
       When your program is compiled in the POSIX environment, the grouplist argument should be defined as follows:

       gid_t	 grouplist[];

       Additionally,  in  the  POSIX environment, if the gidsetsize argument is zero, returns the number of supplemental group IDs associated with
       the calling process, without modifying the array pointed to by the grouplist argument.

See Also
       setgroups(2), initgroups(3x)

																      getgroups(2)

Check Out this Related Man Page

GETGROUPS(2)						      BSD System Calls Manual						      GETGROUPS(2)

NAME
getgroups -- get group access list SYNOPSIS
#include <unistd.h> int getgroups(int gidsetsize, gid_t grouplist[]); DESCRIPTION
getgroups() gets the current group access list of the current user process and stores it in the array grouplist[]. The parameter gidsetsize indicates the number of entries that may be placed in grouplist[]. getgroups() returns the actual number of groups returned in grouplist[]. However, no more than {NGROUPS_MAX} will be returned. If gidsetsize is 0, getgroups() returns the number of groups without modifying the grouplist[] array. Calling initgroups(3) to opt-in for supplementary groups will cause getgroups() to return a single entry, the GID that was passed to initgroups(3). To provide compatibility with applications that use getgroups() in environments where users may be in more than {NGROUPS_MAX} groups, a vari- ant of getgroups(), obtained when compiling with either the macros _DARWIN_UNLIMITED_GETGROUPS or _DARWIN_C_SOURCE defined, can be used that is not limited to {NGROUPS_MAX} groups. However, this variant only returns the user's default group access list and not the group list modi- fied by a call to setgroups(2) (either in the current process or an ancestor process). Use of setgroups(2) is highly discouraged, and there is no foolproof way to determine if it has been previously called. RETURN VALUES
A successful call returns the number of groups in the group set. Otherwise, a value of -1 is returned and the global integer variable errno is set to indicate the error. ERRORS
The possible errors for getgroups() are: [EFAULT] The argument grouplist specifies an invalid address. [EINVAL] The argument gidsetsize, although non-zero, is smaller than the number of groups in the group set. LEGACY SYNOPSIS
#include <sys/param.h> #include <sys/types.h> #include <unistd.h> The include files <sys/param.h> and <sys/types.h> are necessary. SEE ALSO
setgroups(2), initgroups(3), compat(5) HISTORY
The getgroups() function call appeared in 4.2BSD. 4.2 Berkeley Distribution October 28, 2011 4.2 Berkeley Distribution
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