echo与read的使用方法

read的使用

功能：显示输入的字符

-p 输入提示文字

-n 输入字符长度限制

-t 输入限时

-s 隐藏输入内容

[root@XX ~]# read -p "hello"
hello
[root@XX ~]# 

echo的使用

功能：显示字符,echo会将输入的字符串送往标准输出，输出的字符串间以空白字符隔开，并在最后加上换行号。

语法：echo [-neE]

选项：

-E 默认，不支持解释功能，""变量会替换，弱引用；''变量不会替换，强引用

-n 不自动换行

-e 启动字符的解释功能，需要加上""或者''

常用的转义字符如下：

a 响铃
 退格(backspace)
e 转义符
c 不换行
f 换页
换行
回车
水平制表符
v 垂直制表符
ONNN 字节数以八进制数 NNN (1 至 3 位）表不
xHH 字节数以十六进制数 HH (1 至 2 位）表不

例：

[root@XX ~]# echo -e 'www.baidu.com
www.google.com'
www.baidu.com 
www.google.com

[root@XX ~]# echo {1..10}
1 2 3 4 5 6 7 8 9 10
[root@XX ~]# echo {1..10..2}
1 3 5 7 9

当使用echo输出命令提花后的内容时，名利执行结果的格式可能会发生变化。

例：

[root@XX ~]# echo ifconfig
ifconfig
[root@XX ~]# echo `ifconfig`
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.11 netmask 255.255.255.0 broadcast 192.168.1.255 inet6 fe80::20c:29ff:fec1:2778 prefixlen 64 scopeid 0x20<link> inet6 2a00:23c4:3d9d:d500:20c:29ff:fec1:2778 prefixlen 64 scopeid 0x0<global> inet6 fdaa:bbcc:ddee:0:20c:29ff:fec1:2778 prefixlen 64 scopeid 0x0<global> ether 00:0c:29:c1:27:78 txqueuelen 1000 (Ethernet) RX packets 41800 bytes 17961825 (17.1 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 5875 bytes 422845 (412.9 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 1000 (Local Loopback) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 52:54:00:22:1b:7e txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@XX ~]# echo "`ifconfig`"
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.11  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::20c:29ff:fec1:2778  prefixlen 64  scopeid 0x20<link>
        inet6 2a00:23c4:3d9d:d500:20c:29ff:fec1:2778  prefixlen 64  scopeid 0x0<global>
        inet6 fdaa:bbcc:ddee:0:20c:29ff:fec1:2778  prefixlen 64  scopeid 0x0<global>
        ether 00:0c:29:c1:27:78  txqueuelen 1000  (Ethernet)
        RX packets 41801  bytes 17961885 (17.1 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5876  bytes 422905 (412.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

virbr0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 192.168.122.1  netmask 255.255.255.0  broadcast 192.168.122.255
        ether 52:54:00:22:1b:7e  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0