[root@Oracle11_2 ~]# ll

total

-rw-------.  root root    May   : anaconda-ks.cfg

drwxr-xr-x.  root root    May  : backup

drwxr-xr-x   root root    May  : Desktop

drwxr-xr-x   root root    May  : Documents

drwxr-xr-x   root root    May  : Downloads

-rw-r--r--.  root root    May   : install.log

-rw-r--r--.  root root    May   : install.log.syslog

drwxr-xr-x   root root    May  : Music

-rw-r--r--   root root  Aug    pdksh-5.2.-.el5_8..x86_64.rpm

drwxr-xr-x   root root    May  : Pictures

drwxr-xr-x   root root    May  : Public

drwxr-xr-x.  root root    May   : scripts

drwxr-xr-x   root root    May  : Templates

drwxr-xr-x   root root    May  : Videos

用户读取目录的权限应该是5(r-x) 而不是 4(r--) ,x意味着有在目录下执行命令的权限。

[root@Oracle11_2 ~]# useradd backup

[root@Oracle11_2 ~]# useradd jingy

[root@Oracle11_2 ~]# su - backup

[backup@Oracle11_2 ~]$ id

uid=(backup) gid=(backup) groups=(backup)

[backup@Oracle11_2 ~]$ exit

logout

[root@Oracle11_2 ~]# su - jingy

[jiongy@Oracle11_2 ~]$ id

uid=(jingy) gid=(jingy) groups=(jingy)

[jiongy@Oracle11_2 ~]$ exit

logout

[root@Oracle11_2 ~]# usermod -a -G backup jingy

[root@Oracle11_2 ~]# su - jingy

[jiongy@Oracle11_2 ~]$ id

uid=(jiongy) gid=(jingy) groups=(jingy),(backup)

[jiongy@Oracle11_2 ~]$ id

uid=(jiongy) gid=(jingy) groups=(jingy),(backup)

usermod -G backup jingy #修改用户次要组信息
usermod -a -G backup jingy #将用户添加到新的次要组中