getgroups(2)getgroups(2)NAMEgetgroups - Get the supplementary group IDs of the current process
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
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.
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.
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.
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.
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.
Functions: getgid(2), setgroups(2), setsid(2), sysconf(2), init‐