S_ISGID 1912 include/linux/fs.h return (ino->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID; S_ISGID 2772 include/linux/fs.h return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP)); S_ISGID 9 include/linux/stat.h #define S_IALLUGO (S_ISUID|S_ISGID|S_ISVTX|S_IRWXUGO)