getgroups(2)							  getgroups(2)

NAME
       getgroups - Get 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 Open  Group  standards,
       but  might  be required on other vendors' systems that conform to these
       standards.

STANDARDS
       Interfaces documented on this reference page conform to industry	 stan‐
       dards as follows:

       getgroups(): XSH4.0, XSH4.2, XSH5.0

       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 sup‐
       plementary group IDs of the process are stored. The effective group  ID
       of the process is not returned by the getgroups() function if it is not
       also a supplementary group ID of the calling 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 IDs than the value indi‐
       cated by the sysconf() parameter _SC_NGROUPS_MAX.

       If the gidsetsize parameter  is	0  (zero),  the	 getgroups()  function
       returns the number of supplementary group IDs associated with the call‐
       ing 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 parameter.
       Otherwise, the function returns a value of -1 and sets errno  to	 indi‐
       cate 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 allo‐
       cated address space  of	the  process.	The  gidsetsize	 parameter  is
       nonzero and smaller than the number of supplementary group IDs.

SEE ALSO
       Commands: groups(1)

       Functions:   getgid(2),	 setgroups(2),	setsid(2),  sysconf(2),	 init‐
       groups(3)

       Standards: standards(5)

								  getgroups(2)

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