osf1 man page for getgroups

getgroups(2)							System Calls Manual						      getgroups(2)

NAME
       getgroups - Gets the supplementary group IDs of the current process

SYNOPSIS
       #include <unistd.h>

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

       Application  developers	may  want  to  specify an #include statement for <sys/types.h> before the one for <unistd.h> if programs are being
       developed for multiple platforms. The additional #include statement is not required on Tru64 UNIX systems or by ISO  or	X/Open	standards,
       but may be required on other vendors' systems that conform to these standards.

STANDARDS
       Interfaces documented on this reference page conform to industry standards as follows:

       getgroups(): XSH4.2

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS
       Indicates  the  number  of entries that can be stored in the array pointed to by the grouplist parameter.  Points to the array in which the
       process' supplementary group IDs are stored.  Element grouplist[0] is the effective group ID of the process.

DESCRIPTION
       The getgroups() function gets the current supplementary group IDs of the calling process.  The list is stored in the array  pointed  to	by
       the grouplist parameter.  The gidsetsize parameter indicates the number of entries that can be stored in this array.

       The  getgroups() function never returns more than NGROUPS_MAX entries. (NGROUPS_MAX is a constant defined in the limits.h header file.)	If
       the gidsetsize parameter is 0 (zero), the getgroups() function returns the number of supplementary group IDs associated	with  the  calling
       process without modifying the array pointed to by grouplist.

RETURN VALUES
       Upon successful completion, the getgroups() function returns the number of elements stored in the array pointed to by the grouplist parame-
       ter. Otherwise, the function returns a value of -1 and sets errno to indicate the error.

ERRORS
       If the getgroups() function fails, errno might be set to one of the following values: [Tru64 UNIX]  The gidsetsize and grouplist parameters
       specify	an  array  that  is  partially	or  completely outside of the allocated address space of the process.  The gidsetsize parameter is
       nonzero and smaller than the number of supplementary group IDs.

RELATED INFORMATION
       Commands: groups(1)

       Functions: setgroups(2), getgid(2), setsid(2), initgroups(3)

       Standards: standards(5) delim off

																      getgroups(2)