linux学习练习

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@localhost etc]# cp -r /etc/skel /home/tuser1
[root@localhost ~]# getfacl /home/tuser1/
getfacl: Removing leading ‘/’ from absolute path names
# file: home/tuser1/
# owner: root
# group: root
user::rwx
group::r-x
other::r-x
[root@localhost ~]# setfacl -m g::0 /home/tuser1/
[root@localhost ~]# setfacl -m o::0 /home/tuser1/
[root@localhost ~]# getfacl /home/tuser1/
getfacl: Removing leading ‘/’ from absolute path names
# file: home/tuser1/
# owner: root
# group: root
user::rwx
group::—
other::—

2、编辑/etc/group文件，添加组hadoop。

[root@localhost ~]# echo “hadoop:x:1001:” >> /etc/group
[root@localhost ~]# cat /etc/group | grep 1001
hadoop:x:1001:

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@localhost ~]# echo “hadoop:x:1001:1001::/home/hadoop:bin/bash” >> /etc/passwd
[root@localhost ~]# cat /etc/passwd | grep 1001
hadoop:x:1001:1001::/home/hadoop:bin/bash

4、复制/etc/skel目录为/home/hadoop，要求修改hadoop目录的属组和其它用户没有任何访问权限。
[root@localhost ~]# cp -rv /etc/skel /home/hadoop
‘/etc/skel’ -> ‘/home/hadoop’
‘/etc/skel/.bash_logout’ -> ‘/home/hadoop/.bash_logout’
‘/etc/skel/.bash_profile’ -> ‘/home/hadoop/.bash_profile’
‘/etc/skel/.bashrc’ -> ‘/home/hadoop/.bashrc’
[root@localhost ~]# setfacl -m g::0,o::0 /home/hadoop
[root@localhost ~]# getfacl /home/hadoop/
getfacl: Removing leading ‘/’ from absolute path names
# file: home/hadoop/
# owner: root
# group: root
user::rwx
group::—
other::—

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@localhost ~]# chown -R hadoop:hadoop /home/hadoop
[root@localhost ~]# ls -al /home/hadoop/
total 12
drwx——. 2 hadoop hadoop 62 Jul 15 18:03 .
drwxr-xr-x. 8 root root 93 Jul 15 18:03 ..
-rw-r–r–. 1 hadoop hadoop 18 Jul 15 18:03 .bash_logout
-rw-r–r–. 1 hadoop hadoop 193 Jul 15 18:03 .bash_profile
-rw-r–r–. 1 hadoop hadoop 231 Jul 15 18:03 .bashrc

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@localhost ~]# grep -i “^s” /proc/meminfo
SwapCached: 0 kB
SwapTotal: 6029308 kB
SwapFree: 6029308 kB
Shmem: 27776 kB
Slab: 294320 kB
SReclaimable: 201144 kB
SUnreclaim: 93176 kB

[root@localhost ~]# egrep “^(s|S)” /proc/meminfo
SwapCached: 0 kB
SwapTotal: 6029308 kB
SwapFree: 6029308 kB
Shmem: 27776 kB
Slab: 294320 kB
SReclaimable: 201144 kB
SUnreclaim: 93176 kB

7、显示/etc/passwd文件中其默认shell为非/sbin/nologin的用户；
[root@localhost ~]# cat /etc/passwd | grep -v “/sbin/nologin” | cut -d: -f1
root
sync
shutdown
halt
user3
mageia
slackware
hadoop

8、显示/etc/passwd文件中其默认shell为/bin/bash的用户；
[root@localhost grub2]# cat /etc/passwd | grep “/bin/bash” | cut -d: -f1
root
user3
mageia

9、找出/etc/passwd文件中的一位数或两位数；
[root@localhost ~]# grep “\<[0-9]\{1,2\}\>” /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
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
apache:x:48:48:Apache:/usr/share/httpd:/sbin/nologin
mysql:x:27:27:MariaDB Server:/var/lib/mysql:/sbin/nologin

10、显示/boot/grub/grub.conf中以至少一个空白字符开头的行；
[root@localhost ~]#grep “^[[:space:]]\+” /boot/grub/grub.conf

11、显示/etc/rc.d/rc.sysinit文件中以#开头，后面跟至少一个空白字符，而后又有至少一个非空白字符的行；
[root@localhost grub2]# grep “^[[:space:]]\+[^[:space:]]” /etc/rc.d/rc.sysinit

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@localhost grub2]# 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
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
tcp6 0 0 :::80 :::* LISTEN
tcp6 0 0 :::21 :::* LISTEN
tcp6 0 0 :::22 :::* LISTEN
tcp6 0 0 ::1:25 :::* LISTEN

13、添加用户bash, testbash, basher, nologin (此一个用户的shell为/sbin/nologin)，而后找出当前系统上其用户名和默认shell相同的用户的信息；
[root@localhost grub2]# useradd bash
[root@localhost grub2]# useradd testbash
[root@localhost grub2]# useradd basher
[root@localhost grub2]# useradd -s /sbin/nologin nologin
[root@localhost grub2]# egrep “^([^:]+\>).*\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:2003:2003::/home/bash:/bin/bash
nologin:x:2006:2006::/home/nologin:/sbin/nologin