getgid

GETGID(2)                     System Calls Manual                    GETGID(2)

NAME
     getgid, getegid — get group process identification

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     gid_t
     getgid(void);

     gid_t
     getegid(void);

DESCRIPTION
     The getgid() system call returns the real group ID of the calling
     process, getegid() returns the effective group ID of the calling process.

     The real group ID is specified at login time.

     The real group ID is the group of the user who invoked the program.  As
     the effective group ID gives the process additional permissions during
     the execution of “set-group-ID” mode processes, getgid() is used to
     determine the real-user-id of the calling process.

ERRORS
     The getgid() and getegid() system calls are always successful, and no
     return value is reserved to indicate an error.

SEE ALSO
     getuid(2), issetugid(2), setgid(2), setregid(2)

STANDARDS
     The getgid() and getegid() system calls are expected to conform to
     ISO/IEC 9945-1:1990 (“POSIX.1”).

                               December 15, 2015