newgrp
log in to a new group 【SYNOPSIS】 newgrp [-] [group] 这个命令只是在用户的主属组更换的时候有用，例如USERNAME有主属组group1，附属组group2，group3;现在切换用户的主属组为group3则使用此命令
总结描述用户和组管理类命令的使用方法并完成练习
创建组distro，其GID为2016； [root@localhost ~]# groupadd -g 2016 distro [root@localhost ~]# tail -1 /etc/group distro:x:2016: 创建用户mandriva，其ID为1005；基本组位distro； [root@localhost ~]# useradd -g distro -u 1005 mandriva [root@localhost ~]# tail -1 /etc/passwd mandriva:x:1005:2016::/home/mandriva:/bin/bash 创建用户mageia，其ID位1100；家目录为/home/linux； [root@localhost ~]# useradd -u 1100 -d /home/linux mageia [root@localhost ~]# tail -1 /etc/passwd mageia:x:1100:1100::/home/linux:/bin/bash 给用户mageia添加密码，密码为mageedu； [root@localhost ~]# passwd mageia Changing password for user mageia. New password: Retype new password: passwd: all authentication tokens updated successfully. 删除用户mandriva但保留其家目录； [root@localhost ~]# tail -3 /etc/passwd mariadb:x:1000:1000::/home/mariadb:/sbin/nologin hadoop:x:1001:1001::/home/hadoop:/bin/bash mageia:x:1100:1100::/home/linux:/bin/bash [root@localhost ~]# ls /home/ hadoop linux mandriva 创建用户slackware，其ID为2002，基本组为distro，附属组为peguin； [root@localhost ~]# groupadd peguin [root@localhost ~]# useradd -u 2002 -g distro -Gpeguin slackware [root@localhost ~]# tail -2 /etc/passwd mageia:x:1100:1100::/home/linux:/bin/bash slackware:x:2002:2016::/home/slackware:/bin/bash [root@localhost ~]# tail -2 /etc/group mageia:x:1100: peguin:x:2017:slackware 修改slackware的默认shell为/bin/tcsh； [root@localhost ~]# usermod -s /bin/tcsh slackware [root@localhost ~]# tail -2 /etc/passwd mageia:x:1100:1100::/home/linux:/bin/bash slackware:x:2002:2016::/home/slackware:/bin/tcsh 为用户slackware新增附属组admins； [root@localhost ~]# usermod -aG admins slackware [root@localhost ~]# tail -4 /etc/group distro:x:2016: mageia:x:1100: peguin:x:2017:slackware admins:x:2018:slackware 为slackware添加密码，且要求密码最短使用期限为3天，最长为180天，警告为3天； [root@localhost ~]#passwd -n 3 -x 180 -w 3 slackware [root@localhost ~]# tail -1 /etc/shadow slackware:!!:16658:3:180:3::: [root@localhost ~]#echo 'Slackware'|passwd --stdin slackware 添加用户openstack，其ID号为3003，基本组为clouds，附加组为peguin和nova； [root@localhost ~]# groupadd clouds [root@localhost ~]# groupadd nova [root@localhost ~]# useradd openstack -u 3003 -g clouds -G peguin,nova [root@localhost ~]# tail -1 /etc/passwd openstack:x:3003:2019::/home/openstack:/bin/bash 添加系统用户mysql，要求其shell为/sbin/nologin； [root@localhost ~]# useradd -r mysql -s /sbin/nologin [root@localhost ~]# tail -1 /etc/passwd mysql:x:996:994::/home/mysql:/sbin/nologin 使用echo命令，非交互为openstack添加密码 [root@localhost ~]# echo 'Openstack'|passwd --stdin openstack Changing password for user openstack. passwd: all authentication tokens updated successfully.
