N25-第七周博客作业

1、创建一个10G分区，并格式为ext4文件系统；

(1) 要求其block大小为2048, 预留空间百分比为2, 卷标为MYDATA, 默认挂载属性包含acl；
(2) 挂载至/data/mydata目录，要求挂载时禁止程序自动运行，且不更新文件的访问时间戳；

查看当前分区情况
[root@han ~]# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000c622b

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26        3851    30720000   83  Linux
/dev/sda3            3851        3876      204800   82  Linux swap / Solaris
创建新分区
[root@han ~]# fdisk /dev/sda
创建扩展分区
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
e
Selected partition 4
First cylinder (3876-5221, default 3876):
Using default value 3876
Last cylinder, +cylinders or +size{K,M,G} (3876-5221, default 5221):
Using default value 5221
Command (m for help): p

Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000c622b

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26        3851    30720000   83  Linux
/dev/sda3            3851        3876      204800   82  Linux swap / Solaris
/dev/sda4            3876        5221    10807058+   5  Extended

创建逻辑分区
Command (m for help): n
First cylinder (3876-5221, default 3876):
Using default value 3876
Last cylinder, +cylinders or +size{K,M,G} (3876-5221, default 5221): +10G

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

重新读取分区表
[root@han ~]# partx -a /dev/sda
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
[root@han ~]# partx -a /dev/sda
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
BLKPG: Device or resource busy
error adding partition 4
BLKPG: Device or resource busy
error adding partition 5

查看系统识别的分区
[root@han ~]# cat /proc/partitions
major minor  #blocks  name

   8        0   41943040 sda
   8        1     204800 sda1
   8        2   30720000 sda2
   8        3     204800 sda3
   8        4         31 sda4
   8        5   10485727 sda5

查看磁盘分区情况
[root@han ~]# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000c622b

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26        3851    30720000   83  Linux
/dev/sda3            3851        3876      204800   82  Linux swap / Solaris
/dev/sda4            3876        5221    10807058+   5  Extended
/dev/sda5            3876        5181    10485727   83  Linux

格式化分区
[root@han ~]# mke2fs -t ext4 -b 2048 -m 2 -L MYDATA /dev/sda5  

开启默认挂载特性
[root@han ~]# tune2fs -o acl  /dev/sda5
挂载分区
[root@han ~]# mount -o  noexec,noatime /dev/sda5 /data/mydata

2、创建一个大小为1G的swap分区，并创建好文件系统，并启用之；

创建1G的分区
[root@han ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x24980e07.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 
Value out of range.
Partition number (1-4): 1
First cylinder (1-2610, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): +1G

Command (m for help): p

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x24980e07

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         132     1060258+  83  Linux

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

重新读取分区表
[root@han ~]# partx -a /dev/sdb
BLKPG: Device or resource busy
error adding partition 1
[root@han ~]# cat /proc/partitions 
major minor  #blocks  name

   8        0   41943040 sda
   8        1     204800 sda1
   8        2   30720000 sda2
   8        3     204800 sda3
   8        4          1 sda4
   8        5   10485727 sda5
   8       16   20971520 sdb
   8       17    1060258 sdb1

格式化swap分区
[root@han ~]# mkswap /dev/sdb1
Setting up swapspace version 1, size = 1060252 KiB
no label, UUID=7597f39c-fe1a-4dea-957e-dc051b2a9be8

查看分区使用情况
[root@han ~]# free -m
             total       used       free     shared    buffers     cached
Mem:           980        163        817          0         15         56
-/+ buffers/cache:         90        889
Swap:          199          0        199

启动swap分区
[root@han ~]# swapon /dev/sdb1

[root@han ~]# free -m
             total       used       free     shared    buffers     cached
Mem:           980        163        816          0         15         56
-/+ buffers/cache:         91        889
Swap:         1235          0       1235

查看分区uuid和类型
[root@han ~]# blkid
/dev/sda5: LABEL="MYDATA" UUID="4721b08d-3ed8-4ad8-a4cf-215cc15b1a3a" TYPE="ext4" 
/dev/sda1: UUID="5576bf88-a991-4af9-b8a7-ff55f6f5a67f" TYPE="ext4" 
/dev/sda2: UUID="1cc68cb8-0de5-4cbf-ad1c-b6ed129b1177" TYPE="ext4" 
/dev/sda3: UUID="9ee78e6e-d386-4af2-90e7-17bd0f594d06" TYPE="swap" 
/dev/sdb1: UUID="7597f39c-fe1a-4dea-957e-dc051b2a9be8" TYPE="swap"

3、写一个脚本

(1)、获取并列出当前系统上的所有磁盘设备；
(2)、显示每个磁盘设备上每个分区相关的空间使用信息；

#!/bin/bah
# 显示当前系统所有磁盘分区的使用情况

disk=$(fdisk -l | grep "^Disk /dev/sd[a-z]" | awk -F [:" "] '{print $2}')
echo -e "磁盘设备有:\n$disk"

echo "磁盘的分区使用情况如下:"
df

执行结果:
[root@han scripts]# bash diskinfo.sh
磁盘设备有:
/dev/sda
/dev/sdb
磁盘的分区使用情况如下:
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/sda2       30106576 3515944  25054632  13% /
tmpfs             502068       0    502068   0% /dev/shm
/dev/sda1         194241   34123    149878  19% /boot

4、总结RAID的各个级别及其组合方式和性能的不同；

RAID-0:  
将几块磁盘并行组织起来,当作一块磁盘使用
raid控制器将数据分成若干chunck,再平均存储到不同的磁盘上去耐用性下降,出错几率上升, 存储非关键性数据
    读、写性能提升；
    可用空间：N*min(S1,S2,...)
    无容错能力
    最少磁盘数：2, 2+

RAID-1： 
    读性能提升、写性能略有下降；
    可用空间：1*min(S1,S2,...)
    有冗余能力
    最少磁盘数：2, 2+

RAID-4： 
    最少磁盘数: 3+
    其中一块盘存校验数据(做亦或运算)
    风险高,
    校验盘有性能瓶颈

RAID-5： 
    读、写性能提升
    可用空间：(N-1)*min(S1,S2,...)
    有容错能力：1块磁盘
    最少磁盘数：3, 3+
    轮流做校验盘

RAID-6：不常用
        读、写性能提升
        可用空间：(N-2)*min(S1,S2,...)
        有容错能力：2块磁盘
        最少磁盘数：4, 4+
        校验码存两次

混合类型
RAID-10：
        读、写性能提升
        可用空间：N*min(S1,S2,...)/2
        有容错能力：每组镜像最多只能坏一块；
        最少磁盘数：4, 4+

RAID-01: 不常用

        风险比raid10大
        每组坏一个,数据丢失

JBOD：Just a Bunch Of Disks
    功能：将多块磁盘的空间合并一个大的连续空间使用；
    可用空间：sum(S1,S2,...)

常用级别：RAID-0, RAID-1, RAID-5, RAID-10, RAID-50, JBOD

5、创建一个大小为10G的RAID1，要求有一个空闲盘，而且CHUNK大小为128k;

(1)创建分区
[root@lab1 ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): p

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0003bc7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   207888383   103431168   8e  Linux LVM

Command (m for help): n
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p): e
Partition number (3,4, default 3): 3
First sector (207888384-419430399, default 207888384):
Using default value 207888384
Last sector, +sectors or +size{K,M,G} (207888384-419430399, default 419430399):
Using default value 419430399
Partition 3 of type Extended and of size 100.9 GiB is set

Command (m for help): p

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0003bc7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   207888383   103431168   8e  Linux LVM
/dev/sda3       207888384   419430399   105771008    5  Extended

Command (m for help): n
Partition type:
   p   primary (2 primary, 1 extended, 1 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 5
First sector (207890432-419430399, default 207890432):
Using default value 207890432
Last sector, +sectors or +size{K,M,G} (207890432-419430399, default 419430399): +10G
Partition 5 of type Linux and of size 10 GiB is set

Command (m for help): n
Partition type:
   p   primary (2 primary, 1 extended, 1 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 6
First sector (228864000-419430399, default 228864000):
Using default value 228864000
Last sector, +sectors or +size{K,M,G} (228864000-419430399, default 419430399): +10G
Partition 6 of type Linux and of size 10 GiB is set

Command (m for help): p

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0003bc7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   207888383   103431168   8e  Linux LVM
/dev/sda3       207888384   419430399   105771008    5  Extended
/dev/sda5       207890432   228861951    10485760   83  Linux
/dev/sda6       228864000   249835519    10485760   83  Linux

Command (m for help): t
Partition number (1-3,5,6, default 6): 5
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): t
Partition number (1-3,5,6, default 6): 6
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): p

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0003bc7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   207888383   103431168   8e  Linux LVM
/dev/sda3       207888384   419430399   105771008    5  Extended
/dev/sda5       207890432   228861951    10485760   fd  Linux raid autodetect
/dev/sda6       228864000   249835519    10485760   fd  Linux raid autodetect

漏了一个分区，下面补上
Command (m for help): n
Partition type:
   p   primary (2 primary, 1 extended, 1 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 7
First sector (249837568-419430399, default 249837568):
Using default value 249837568
Last sector, +sectors or +size{K,M,G} (249837568-419430399, default 419430399): +10G
Partition 7 of type Linux and of size 10 GiB is set

Command (m for help): p

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0003bc7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   207888383   103431168   8e  Linux LVM
/dev/sda3       207888384   419430399   105771008    5  Extended
/dev/sda5       207890432   228861951    10485760   fd  Linux raid autodetect
/dev/sda6       228864000   249835519    10485760   fd  Linux raid autodetect
/dev/sda7       249837568   270809087    10485760   83  Linux

Command (m for help): t
Partition number (1-3,5-7, default 7): 7
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): p

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0003bc7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   207888383   103431168   8e  Linux LVM
/dev/sda3       207888384   419430399   105771008    5  Extended
/dev/sda5       207890432   228861951    10485760   fd  Linux raid autodetect
/dev/sda6       228864000   249835519    10485760   fd  Linux raid autodetect
/dev/sda7       249837568   270809087    10485760   fd  Linux raid autodetect

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)

[root@lab1 ~]# partx -a /dev/sda
partx: /dev/sda: error adding partitions 1-2
[root@lab1 ~]# partx -a /dev/sda
partx: /dev/sda: error adding partitions 1-3
partx: /dev/sda: error adding partitions 5-7

[root@lab1 ~]# cat /proc/partitions
major minor  #blocks  name

  11        0    4228096 sr0
   8        0  209715200 sda
   8        1     512000 sda1
   8        2  103431168 sda2
   8        3          1 sda3
   8        5   10485760 sda5
   8        6   10485760 sda6
   8        7   10485760 sda7
 253        0  102400000 dm-0
 253        1    1024000 dm-1

（2） 创建raid
[root@lab1 ~]# yum -y install mdadm

[root@lab1 ~]# mdadm -C /dev/md1 -a yes -l 1 -c 128 -n 2 -x 1 /dev/sda{5,6,7}
mdadm: Note: this array has metadata at the start and
    may not be suitable as a boot device.  If you plan to
    store '/boot' on this device please ensure that
    your boot-loader understands md/v1.x metadata, or use
    --metadata=0.90
Continue creating array?
Continue creating array? (y/n) y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.

6、创建一个大小为4G的RAID5设备，chunk大小为256k，格式化ext4文件系统，要求可开机自动挂载至/backup目录，而且不更新访问时间戳，且支持acl功能；

(1)创建3个2G的分区
[root@lab1 ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): n
Partition type:
   p   primary (2 primary, 1 extended, 1 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 8
First sector (270811136-419430399, default 270811136):
Using default value 270811136
Last sector, +sectors or +size{K,M,G} (270811136-419430399, default 419430399): +2G
Partition 8 of type Linux and of size 2 GiB is set

Command (m for help): n
Partition type:
   p   primary (2 primary, 1 extended, 1 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 9
First sector (275007488-419430399, default 275007488):
Using default value 275007488
Last sector, +sectors or +size{K,M,G} (275007488-419430399, default 419430399): +2G
Partition 9 of type Linux and of size 2 GiB is set

Command (m for help): n
Partition type:
   p   primary (2 primary, 1 extended, 1 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 10
First sector (279203840-419430399, default 279203840):
Using default value 279203840
Last sector, +sectors or +size{K,M,G} (279203840-419430399, default 419430399): +2G
Partition 10 of type Linux and of size 2 GiB is set

Command (m for help): p

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0003bc7d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   207888383   103431168   8e  Linux LVM
/dev/sda3       207888384   419430399   105771008    5  Extended
/dev/sda5       207890432   228861951    10485760   fd  Linux raid autodetect
/dev/sda6       228864000   249835519    10485760   fd  Linux raid autodetect
/dev/sda7       249837568   270809087    10485760   fd  Linux raid autodetect
/dev/sda8       270811136   275005439     2097152   83  Linux
/dev/sda9       275007488   279201791     2097152   83  Linux
/dev/sda10      279203840   283398143     2097152   83  Linux

Command (m for help): t
Partition number (1-3,5-10, default 10): 8
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): t
Partition number (1-3,5-10, default 10): 9
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): t
Partition number (1-3,5-10, default 10): 10
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.

[root@lab1 ~]# partx -a /dev/sda
partx: /dev/sda: error adding partitions 1-3
partx: /dev/sda: error adding partitions 5-7
[root@lab1 ~]# partx -a /dev/sda
partx: /dev/sda: error adding partitions 1-3
partx: /dev/sda: error adding partitions 5-10

（2）创建raid
[root@lab1 ~]# mdadm -C /dev/md2 -a yes -l 5 -c 256 -n 3  /dev/sda{8,9,10}
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md2 started.

（3）格式化并挂载
[root@lab1 ~]# mkfs.ext4 /dev/md2
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=64 blocks, Stripe width=128 blocks
262144 inodes, 1047552 blocks
52377 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1073741824
32 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

[root@lab1 ~]# mdadm -D /dev/md2
/dev/md2:
        Version : 1.2
  Creation Time : Tue Feb 21 05:15:06 2017
     Raid Level : raid5
     Array Size : 4190208 (4.00 GiB 4.29 GB)
  Used Dev Size : 2095104 (2046.00 MiB 2145.39 MB)
   Raid Devices : 3
  Total Devices : 3
    Persistence : Superblock is persistent

    Update Time : Tue Feb 21 05:17:54 2017
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 256K

           Name : lab1.tfedu.net:2  (local to host lab1.tfedu.net)
           UUID : 21b997cd:3ad38c23:3838adc4:0a70bce8
         Events : 18

    Number   Major   Minor   RaidDevice State
       0       8        8        0      active sync   /dev/sda8
       1       8        9        1      active sync   /dev/sda9
       3       8       10        2      active sync   /dev/sda10

[root@lab1 ~]# mkdir /backup
[root@lab1 ~]# vim /etc/fstab
/dev/md2 /backup  ext4 defaults,acl,noatime 0 0
[root@lab1 ~]# mount -a
[root@lab1 ~]# mount | grep md2
/dev/md2 on /backup type ext4 (rw,noatime,seclabel,stripe=128,data=ordered)

7、写一个脚本

(1) 接受一个以上文件路径作为参数；
(2) 显示每个文件拥有的行数；
(3) 总结说明本次共为几个文件统计了其行数；

#!/bin/bash
# 统计传入文件的行数

if [ $# -lt 1 ];then
        echo "请输入至少一个参数"
        exit 1
fi

files=0
file_num=$#
while [ $file_num -gt 0 ];do
        if [ -f $1 ];then
                lines=$(cat $1 | wc -l)
                let files+=1
                echo "$1有${lines}行"
        else
                echo "$1 不存在"
        fi

        let file_num-=1
        shift
done
echo "总共有${files}个文件统计了其行数"

执行结果:
[root@localhost ~]# bash  files.sh /etc/issue /etc/fstab 
/etc/issue有3行
/etc/fstab有12行
总共有2个文件统计了其行数

8、写一个脚本

(1) 传递两个以上字符串当作用户名；
(2) 创建这些用户；且密码同用户名；
(3) 总结说明共创建了几个用户；

#!/bin/bash
# 根据传入的字符串创建用户

if [ $# -lt 3 ];then
        echo "请输入至少3个参数"
        exit 1
fi

num=0
file_num=$#
while [ $file_num -gt 0 ];do
        if ! id $1 &> /dev/null;then
                useradd $1
                echo "$1" | passwd --stdin $1 &> /dev/null
                let num+=1
                echo "$1创建成功"
        else
                echo "$1已经存在"
        fi

        let file_num-=1
        shift
done
echo "总共创建了${num}个用户"


执行结果:
[root@localhost ~]# bash createuser.sh zhang
请输入至少3个参数
[root@localhost ~]# bash createuser.sh zhang wang sun
zhang创建成功
wang创建成功
sun创建成功
总共创建了3个用户
[root@localhost ~]# bash createuser.sh zhang wang sun
zhang已经存在
wang已经存在
sun已经存在
总共创建了0个用户

9、写一个脚本，新建20个用户，visitor1-visitor20；计算他们的ID之和；

#!/bin/bash
#创建visitor1-visitor20,并计算id之和

idsum=0
for i in {1..20};do
        if ! id visitor${i} &> /dev/null;then
                useradd visitor${i}
                let idsum+=$(id -u visitor${i})
        else
                echo "用户visitor${i}已存在"
        fi
done

echo "创建的用户id之和为: $idsum"

执行结果: 
[root@localhost ~]# bash createuser2.sh
创建的用户id之和为: 20270