1.复制/etc/skel目录为/home/tuser1，要求/home/tuser1及其内部文件的属组和其他用户均没有任何访问权限
[root@centos-7 ~]# cp -r /etc/skel /home/tuser1
[root@centos-7 ~]# chmod -R 700 /home/tuser1
[root@centos-7 ~]# ls -al /home/tuser1/
total 12
drwx------. 4 root root 90 Nov 21 18:28 .
drwxr-xr-x. 16 root root 192 Nov 21 17:57 ..
-rwx------. 1 root root 18 Nov 21 17:57 .bash_logout
-rwx------. 1 root root 193 Nov 21 17:57 .bash_profile
-rwx------. 1 root root 231 Nov 21 17:57 .bashrc
drwx------. 4 root root 39 Nov 21 17:57 .mozilla
drwx------. 3 root root 78 Nov 21 18:28 skel
2.编辑/etc/group文件，添加组hadoop
admins:x:2018:slackware
hadoop:x:8888:
[root@centos-7 ~]# echo "hadoop:x:8888:" >> /etc/group
3.手动编辑/etc/passwd文件新增一行，增加用户hadoop，其基本组ID为hadoop组的ID号；其家目录为/home/hadoop
[root@centos-7 ~]# echo "hadoop:x:8888:8888::/home/hadoop:/bin/bash" >> /etc/passwd
[root@centos-7 ~]# grep 'hadoop' /etc/passwd
hadoop:x:8888:8888::/home/hadoop:/bin/bash
4.复制/etc/skel目录为/home/hadoop，要求修改hadoop目录的属组和其他用户没有任何访问权限
[root@centos-7 ~]# cp -r /etc/skel /home/hadoop
[root@centos-7 ~]# chown -R hadoop /home/hadoop
[root@centos-7 ~]# chgrp -R hadoop /home/hadoop
[root@centos-7 ~]# chmod -R 700 /home/hadoop
5.修改/home/hadoop目录及其内部所有文件的属主为hadoop，属组为hadoop
[root@centos-7 hadoop]# chown -R hadoop /home/hadoop
[root@centos-7 hadoop]# chgrp -R hadoop /home/hadoop
[root@centos-7 hadoop]# ls -al
total 12
drwx------. 4 hadoop hadoop 90 Nov 21 20:13 .
drwxr-xr-x. 17 root root 206 Nov 21 19:33 ..
-rwx------. 1 hadoop hadoop 18 Nov 21 19:33 .bash_logout
-rwx------. 1 hadoop hadoop 193 Nov 21 19:33 .bash_profile
-rwx------. 1 hadoop hadoop 231 Nov 21 19:33 .bashrc
drwx------. 4 hadoop hadoop 39 Nov 21 19:33 .mozilla
drwx------. 3 hadoop hadoop 78 Nov 21 20:13 skel
6.显示/proc/meminfo文件中以大写或小写S开头的行，用两种方式
[root@centos-7]# grep "^[Ss]" /proc/meminfo
[root@centos-7]# grep -i ^'s' /proc/meminfo
7.显示/etc/passwd文件中其默认shell为非/sbin/nologin的用户
[root@centos-7 hadoop]# grep '/sbin/nologin'$ /etc/passwd | cut -d: -f1
8.显示/etc/passwd文件中默认shell为/bin/bash用户
[root@centos-7 hadoop]# grep '/bin/bash'$ /etc/passwd | cut -d: -f1
9.找出/etc/paawd文件中的一位数或两位数
grep "\<[0-9]\{1,2\}\>" /etc/passwd
10.显示/boot/grub/grub.conf中以至少一个空白字符开头的行
[root@centos-7 hadoop]# grep "^[[:space:]]\{1,\}" /boot/grub/grub.conf
11.显示/etc/rc.d/rc.sysinit文件中以#开头，后面至少一个空白字符，而后面至少一个非空白字符的行
[root@centos-7 hadoop]# grep "^#[[:space:]]\{1,\}[^[:space:]]\{1,\}" /etc/rc.d/rc.local
# THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES
# It is highly advisable to create own systemd services or udev rules
# to run scripts during boot instead of using this file.
# In contrast to previous versions due to parallel execution during boot
# this script will NOT be run after all other services.
# Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure
# that this script will be executed during boot.
12.打出netstat -tan命令执行结果中以 LISTEN，后或跟空白符结尾的行
[root@centos-7 hadoop]# netstat -tan | grep "\<LISTEN\>\|[[:space:]]\{0,\}$"
13.添加用户bash,testbash,basher,nologin(此用户的shell为/sbin/nologin),而后找出系统上其用户名和默认shell相同的用户的信息
[root@centos-7 ~]# grep "\(^.*\):.*\1$" /etc/passwd
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
bash:x:1003:1007::/home/bash:/bin/bash
sh:x:1006:1010::/home/sh:/bin/bash
nologin:x:1007:1011::/sbin/nologin:/sbin/nologin
