root@dongo:/nfs/www/ru/forum# su www-data
sh-3.1$ ls -l
total 8
drwx--x--x  2 uru_forum uru_forum 4096 Feb  5 23:11 bin
drwxrwx--- 10 uru_forum uru_forum 4096 Feb  9 11:04 htdocs
sh-3.1$ cd htdocs/
sh: cd: htdocs/: Permission denied
sh-3.1$ id
uid=33(www-data) gid=33(www-data) groups=33(www-data),1007(ubuntu_de),1013(ubuntu_fr),1018(ufr_auth),1019(ufr_doc),1020(ufr_forum),1022(ufr_planet),1024(ufr_www),1029(ubuntu_no),1031(ubuntu_ru),1048(ubuntu_ir),1049(ufr_static),1052(ubuntu_ku),1054(ubuntu_il),1056(uil_www),1057(uru_www),1058(uru_forum),1059(uku_www),1060(uno_www),1061(uno_forum),65534(nogroup)