权限管理和文本过滤

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它用户均没有任何访问权限

[root@study ~]# cp -r /etc/skel/ /home/tuser1|chmod -R 700 tuser1/
[root@study home]# ll
total 4
drwx------. 4 kang      kang     4096 Nov  1 06:41 kang
drwx------. 2      1100     1100   59 Nov 14 07:40 linux
drwx------. 2 mandriva  distro     59 Nov 14 07:38 mandriva
drwx------. 2 mysql     mysql      59 Nov 14 08:09 mysql
drwx------. 2 openstack clouds     59 Nov 14 08:06 openstack
drwx------. 2 slackware distro     59 Nov 14 07:51 slackware
drwx------. 2 root      root       59 Nov 21 04:36 tuser1
drwx------. 2 xiaokang  xiaokang   79 Nov 14 08:28 xiaokang

2.编辑/etc/group文件，添加组hadoop

[root@study home]# vi /etc/group
mysql:x:3004:
hadoop:x:3009
"/etc/group" 48L, 677C written

3.手动编辑/etc/passwd文件新增一行，添加用户hadoop,其基本组ID为hadoop组的id号；其家目录为/home/hadoop

[root@study home]# vi /etc/passwd
mysql:x:3004:3004::/home/mysql:/sbin/nologin
hadoop:x:3009:3009::/home/hadoop:/sbin/nologin
~
"/etc/passwd" 28L, 1367C written
[root@study home]# id hadoop
uid=3009(hadoop) gid=3009(hadoop) groups=3009(hadoop)

4.复制/etc/skel目录为/home/hadoop,要求修改hadoop目录的属组合其他用户没有任何访问权限

[root@study home]# cp -r /etc/skel/ /home/hadoop|chmod -R 700 /home/hadoop
[root@study home]# ll
total 4
drwx------. 3 root      root       70 Nov 21 04:55 hadoop

5.修改/home/hadoop目录及其内部所有文件的属主为hadoop

[root@study home]# chown -R hadoop:hadoop hadoop/|ll
total 4
drwx------. 3 root      root       70 Nov 21 04:55 hadoop

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@study home]# grep -E "^[s|S]" /proc/meminfo 
SwapCached:            0 kB
SwapTotal:       2097148 kB
SwapFree:        2097148 kB
Shmem:              6788 kB
Slab:              52804 kB
SReclaimable:      17856 kB
SUnreclaim:        34948 kB

[root@study home]# grep -i "^s" /proc/meminfo 
SwapCached:            0 kB
SwapTotal:       2097148 kB
SwapFree:        2097148 kB
Shmem:              6816 kB
Slab:              52848 kB
SReclaimable:      17824 kB
SUnreclaim:        35024 kB

7.显示/etc/passwd文件中默认shell为非/sbin/nologin的用户

[root@study home]# grep -v "/sbin/nologin" /etc/passwd|cut -d: -f1  
root
sync
shutdown
halt
kang
xiaokang
mandriva
slackware
openstack

8.显示/etc/passwd文件中其默认shell为/bin/bash的用户

[root@study home]# grep '/bin/bash' /etc/passwd|cut -d: -f1
root
kang
xiaokang
mandriva
openstack

9.找出/etc/passwd文件中的一位数或两位数

[root@study home]# grep -o "[0-9]\{1,2\}" /etc/passwd

10.显示/boot/grub2/grub.cfg中已至少一个空白字符开头的行

grep "^[[:space:]]\+" /boot/grub2/grub.cfg

11.显示/etc/rc.d/rc.local文件中以#开头，后面跟至少一个空白字符， 而后又只少一个非空白字符的行

[root@study home]# grep "^#[[:space:]]\+[^[:space:]]\+" /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

12.打出netstat -tan命令执行结果中以'LISTEN'，后或跟空白字符结尾的行

[root@study home]# netstat -tan|grep "LISTEN[[:space:]]*$"
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN     
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN

13.添加用户bash，testbash,basher,nologin(此一个用户的shell为/bin/nologin)， 而后找出当前系统其用户名和默认shell相同的用户的信息

[root@study ~]#  grep "^\([a-z]*\>\).*\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:3010:3010::/home/bash:/bin/bash
nologin:x:3013:3013::/home/nologin:/bin/nologin