第18章Permission

18.1. User

18.1.1. Add a new user

$ adduser neo

## 添加一个账号和root有一样的权限
useradd -o -u 0 -g 0 admin## 指定家目录和shell
useradd -o -u 0 -g 0 -d /root -s /bin/bash admin## 添加 root 用户并且设置密码
useradd -o -u 0 -g 0 admin
echo redhat | passwd admin --stdin
// 上面两条同下面一条
useradd -o -u 0 -g 0 -p $(openssl passwd -1 redhat&＃64;&＃64;neo) admin## 添加普通用户并且设置密码
useradd -p $(openssl passwd -1 redhat&＃64;&＃64;admin) admin## 添加普通用户指定其第二用户组
useradd -G root -p $(openssl passwd -1 redhat&＃64;&＃64;admin) admin

18.1.2. remove an existed user

remove an existed user, but keeping directory /home/neo

$ userdel neo

delete user&＃39;s directory under /home when removing an existed user

$ userdel -r neo

18.1.3. usermod - modify a user account

usermod -G group -a user[root&＃64;scientific ~]# groupadd vm
[root&＃64;scientific ~]# adduser xen
[root&＃64;scientific ~]# usermod -G vm -a xen
[root&＃64;scientific ~]# usermod -G vm -a kvm
[root&＃64;scientific ~]# id xen
uid&＃61;501(xen) gid&＃61;502(xen) groups&＃61;502(xen),501(vm)

18.1.4. lock / unlock

passwd -l neo

passwd -u neo

18.1.4.1. /etc/passwd

[root&＃64;test ~]# cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
news:x:9:13:news:/etc/news:
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
gopher:x:13:30:gopher:/var/gopher:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
nscd:x:28:28:NSCD Daemon:/:/sbin/nologin
vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin
pcap:x:77:77::/var/arpwatch:/sbin/nologin
rpc:x:32:32:Portmapper RPC user:/:/sbin/nologin
mailnull:x:47:47::/var/spool/mqueue:/sbin/nologin
smmsp:x:51:51::/var/spool/mqueue:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin
nfsnobody:x:4294967294:4294967294:Anonymous NFS User:/var/lib/nfs:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
avahi:x:70:70:Avahi daemon:/:/sbin/nologin
haldaemon:x:68:68:HAL daemon:/:/sbin/nologin
avahi-autoipd:x:100:102:avahi-autoipd:/var/lib/avahi-autoipd:/sbin/nologin
neo:x:500:500::/home/neo:/bin/bash
mysql:x:501:501::/home/mysql:/bin/bash