shell 编程 (6)echo read -e \n \c 重定向

echo str

1. 显示普通字符串

echo "str"

可不带""

双引号可转义\"str\"

eg:

[root@k8s-master test2]# echo str
str
[root@k8s-master test2]# echo "str"
str
[root@k8s-master test2]# echo \"str\"
"str"
[root@k8s-master test2]# echo "\"str\""
"str"
[root@k8s-master test2]# 

2. read

从标准输入中读取一行，把输入行中整个字段的值赋给shell变量

eg:

[root@k8s-master test2]# sh t0.sh 
a b c
a b c is input arg
[root@k8s-master test2]# cat t0.sh 
#!/bin/bash

read in_arg
echo "$in_arg is input arg"
[root@k8s-master test2]# 

3. -e

开启转义

\n 换行

\c 不换行

eg:

[root@k8s-master test2]# echo -e "hello\nworld"
hello
world
[root@k8s-master test2]# echo "hello\nworld"
hello\nworld
[root@k8s-master test2]# 

[root@k8s-master test2]# ./t1.sh 
hello! world
[root@k8s-master test2]# cat t1.sh 
#!/bin/bash

echo -e "hello! \c"
echo "world"
[root@k8s-master test2]# 

4. 定向至文件

echo只能一行,cat 结合eof能多行

[root@k8s-master test2]# echo "hello world" > hello.txt
[root@k8s-master test2]# cat hello.txt 
hello world
[root@k8s-master test2]# 

[root@k8s-master test2]# cat world.txt 

[root@k8s-master test2]# cat > world.txt <<EOF      
abc
def
EOF

[root@k8s-master test2]# cat ./world.txt 
abc
def
[root@k8s-master test2]# cat <<EOF >world1.txt
> abc
> def
> hello
> EOF
[root@k8s-master test2]# cat ./world1.txt 
abc
def
hello
[root@k8s-master test2]# 

5. 原样输出

单引号

6. 显示命令执行结果

反引号``