1、列出当前系统上所有已经登录的用户的用户名，注意：同一个用户登录多次，则只显示一次即可。

[jizo@jizo ~]$ who | cut -d" " -f1 | uniq

jizo

 2、取出最后登录到当前系统的用户的相关信息。

[root@jizo ~]# who | tail -l

jizo     :0           2016-12-18 15:00 (:0)

jizo     tty2         2016-12-18 15:01

jizo     pts/0        2016-12-18 15:14 (192.168.1.5) 

3、取出当前系统上被用户当作其默认shell的最多的那个shell。

[root@jizo ~]# cut -d: -f7 /etc/passwd | uniq -c | sort -n | tail -1

     21 /sbin/nologin

4、将/etc/passwd中的第三个字段数值最大的后10个用户信息全部改为大写后保存至/tmp/maxusers.txt文件中。

[root@jizo ~]# sort -t: -k3 -n /etc/passwd | tail -10 | tr 'a-z' 'A-Z' > /tmp/maxusers.txt

[root@jizo ~]# cat /tmp/maxusers.txt

COLORD:X:992:990:USER FOR COLORD:/VAR/LIB/COLORD:/SBIN/NOLOGIN

SASLAUTH:X:993:76:SASLAUTHD USER:/RUN/SASLAUTHD:/SBIN/NOLOGIN

UNBOUND:X:994:991:UNBOUND DNS RESOLVER:/ETC/UNBOUND:/SBIN/NOLOGIN

SSSD:X:995:993:USER FOR SSSD:/:/SBIN/NOLOGIN

POLKITD:X:996:994:USER FOR POLKITD:/:/SBIN/NOLOGIN

SYSTEMD-NETWORK:X:997:995:SYSTEMD NETWORK MANAGEMENT:/:/SBIN/NOLOGIN

SYSTEMD-BUS-PROXY:X:998:996:SYSTEMD BUS PROXY:/:/SBIN/NOLOGIN

ODS:X:999:998:SOFTHSM PRIVATE KEYS OWNER://VAR/LIB/SOFTHSM:/SBIN/NOLOGIN

JIZO:X:1000:1000:JIZO:/HOME/JIZO:/BIN/BASH

NFSNOBODY:X:65534:65534:ANONYMOUS NFS USER:/VAR/LIB/NFS:/SBIN/NOLOGIN

5、取出当前主机的ip地址，提示：对ifconfig命令的结果进行切分。

[root@jizo ~]# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

       valid_lft forever preferred_lft forever

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: enp12s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:26:18:af:fd:31 brd ff:ff:ff:ff:ff:ff

    inet 192.168.1.3/24 brd 192.168.1.255 scope global dynamic enp12s0

       valid_lft 11847sec preferred_lft 11847sec

    inet6 fe80::226:18ff:feaf:fd31/64 scope link 

       valid_lft forever preferred_lft forever

3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN 

    link/ether 52:54:00:6c:f9:31 brd ff:ff:ff:ff:ff:ff

    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0

       valid_lft forever preferred_lft forever

4: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN qlen 500

    link/ether 52:54:00:6c:f9:31 brd ff:ff:ff:ff:ff:ff

[root@jizo ~]# ifconfig enp12s0 | grep -o "inet .*" | cut -d" " -f2

192.168.1.3

6、列出/etc目录下所有以.conf结尾的文件的文件名，并将其名字转换为大写后保存至/tmp/etc.conf文件中。

[root@jizo ~]# ls /etc/*.conf | tr 'a-z' 'A-Z' > /tmp/etc.conf

[root@jizo ~]# cat /tmp/etc.conf

/ETC/ANT.CONF

/ETC/ASOUND.CONF

/ETC/AUTOFS.CONF

/ETC/AUTOFS_LDAP_AUTH.CONF

/ETC/BRLTTY.CONF

/ETC/CGCONFIG.CONF

/ETC/CGRULES.CONF

/ETC/CGSNAPSHOT_BLACKLIST.CONF

/ETC/CHRONY.CONF

/ETC/DLEYNA-SERVER-SERVICE.CONF

/ETC/DNSMASQ.CONF

/ETC/DRACUT.CONF

/ETC/E2FSCK.CONF

/ETC/EXTLINUX.CONF

/ETC/FPRINTD.CONF

/ETC/FUSE.CONF

/ETC/GEOIP.CONF

/ETC/HBA.CONF

/ETC/HOST.CONF

/ETC/IDMAPD.CONF

/ETC/IPSEC.CONF

/ETC/KDUMP.CONF

/ETC/KRB5.CONF

/ETC/KSMTUNED.CONF

/ETC/LD.SO.CONF

/ETC/LIBAUDIT.CONF

/ETC/LIBUSER.CONF

/ETC/LOCALE.CONF

/ETC/LOGROTATE.CONF

/ETC/MAN_DB.CONF

/ETC/MKE2FS.CONF

/ETC/MTOOLS.CONF

/ETC/NAMED.CONF

/ETC/NFSMOUNT.CONF

/ETC/NSSWITCH.CONF

/ETC/NTP.CONF

/ETC/NUMAD.CONF

/ETC/ODDJOBD.CONF

/ETC/PBM2PPA.CONF

/ETC/PCP.CONF

/ETC/PEAR.CONF

/ETC/PNM2PPA.CONF

/ETC/RADVD.CONF

/ETC/REQUEST-KEY.CONF

/ETC/RESOLV.CONF

/ETC/RSYNCD.CONF

/ETC/RSYSLOG.CONF

/ETC/SESTATUS.CONF

/ETC/SLP.CONF

/ETC/SOFTHSM2.CONF

/ETC/SOS.CONF

/ETC/SUDO.CONF

/ETC/SUDO-LDAP.CONF

/ETC/SYSCTL.CONF

/ETC/TCSD.CONF

/ETC/TROLLTECH.CONF

/ETC/UPDATEDB.CONF

/ETC/USB_MODESWITCH.CONF

/ETC/VCONSOLE.CONF

/ETC/WVDIAL.CONF

/ETC/YUM.CONF

7、显示出/var目录下一级子目录或文件总个数。

[root@jizo ~]# ll -a /var/ | wc -l

29

8、取出/etc/group文件中第三个字段数值最小的10个组的名字。

[root@jizo ~]# cat /etc/group | sort -t : -k3 -n -r | tail -10

kmem:x:9:

mem:x:8:

lp:x:7:

disk:x:6:

tty:x:5:

adm:x:4:

sys:x:3:

daemon:x:2:

bin:x:1:

root:x:0:

9、将/etc/fstab和/etc/issue文件的内容合并为同一个内容后保存至/tmp/etc.test文件中。

[root@jizo ~]# cat /etc/fstab /etc/issue > /tmp/etc.test

[root@jizo ~]# cat /tmp/etc.test

#

# /etc/fstab

# Created by anaconda on Sun Dec 18 13:24:07 2016

#

# Accessible filesystems, by reference, are maintained under '/dev/disk'

# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

#

/dev/mapper/centos-root /                       xfs     defaults        0 0

UUID=e60127bf-5bec-4b52-82dd-fc0048ac2f67 /boot                   xfs     defaults        0 0

/dev/mapper/centos-home /home                   xfs     defaults        0 0

/dev/mapper/centos-swap swap                    swap    defaults        0 0

\S

Kernel \r on an \m

10、请总结描述用户和组管理类命令的使用方法并完成一下练习：

1）创建组distro，其GID为2016

[root@jizo ~]# groupadd -g 2016 distro

2）创建用户mandriva，其ID号为1005；基本组为distro

[root@jizo ~]# useradd -u 1005 -g distro mandreva

3）创建用户mageia，其ID号为1100，家目录为/home/linux

[root@jizo ~]# useradd -u 1100 -d /home/liunx mageia

4）给用户mageia添加密码，密码为mageedu

[root@jizo ~]# echo "mageedu" | passwd –stdin mageia

Changing password for user mageia.

passwd: all authentication tokens updated successfully.

5）删除mandriva，但保留其家目录

[root@jizo ~]# userdel mandriva

6）创建用户slackware，其ID号为2002，基本组为distro，附加组peguin

[root@jizo ~]# groupadd peguin

[root@jizo ~]# useradd -u 2002 -g distro -G peguin slackware

7）修改slackware的默认shell为/bin/tcsh

[root@jizo ~]# usermod -s /bin/tcsh slackware

[root@jizo ~]# cat /etc/passwd | grep slackware

slackware:x:2002:2016::/home/slackware:/bin/tcsh

8）为用户slackware新增附加组admins

[root@jizo ~]# groupadd admins

[root@jizo ~]#  usermod -a -G admins slackware

9）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@jizo ~]# passwd -n 3 -x 180 -w 3 slackware

Adjusting aging data for user slackware.

passwd: Success

[root@jizo ~]# cat /etc/shadow | grep slackware

slackware:!!:17153:3:180:3:::

10）添加用户openstack，其ID为3003，基本组为clouds，附加组为peguin和nova

[root@jizo ~]# useradd -u 3003 -g clouds -G peguin,nova openstack

useradd: group 'clouds' does not exist

[root@jizo ~]# groupadd clouds

[root@jizo ~]# useradd -u 3003 -g clouds -G peguin,nova openstack

useradd: group 'nova' does not exist

[root@jizo ~]# groupadd nova

[root@jizo ~]# useradd -u 3003 -g clouds -G peguin,nova openstack

11）添加系统用户mysql，要求其shell为/sbin/nologin

[root@jizo ~]# useradd -r -s /sbin/nologin mysql

 12）使用echo命令，非交互式为openstack添加密码

[root@jizo ~]# echo "openstack" | passwd –stdin openstack

Changing password for user openstack.

passwd: all authentication tokens updated successfully.