NAME group_member - test whether a process is in a group LIBRARY Standard C library ... libc , -lc ) SYNOPSIS #include int group_member(gid_t gid ); Feature Test Macro Requiremen…getgid (2), setgid (2), getgrouplist (3), group_member (3), initgroups (3), capabilities (7), credentialsgetgid (2), setgid (2), getgrouplist (3), group_member (3), initgroups (3), capabilities (7), credentialsgetgroups (2), setgroups (2), getgrent (3), group_member (3), group (5), passwdgetgid (2), setgid (2), getgrouplist (3), group_member (3), initgroups (3), capabilities (7), credentialsgetgid (2), setgid (2), getgrouplist (3), group_member (3), initgroups (3), capabilities (7), credentialsuser is not explicitly specified as group member (e.g., in /etc/group ). If the command lslogins