Bash function skill

bash 函数技巧

1. 递归函数

2.导出函数

函数也可以像环境变量一样用 export 导出

➜   foo() {echo "This is foo function"}
➜   export -f foo
foo () {
	echo "This is foo function"
}
➜   foo
This is foo function
➜

3. 读取命令返回值

命令的返回值被保存在变量 $? 中
返回值被称为 退出状态 。它可用于确定命令执行成功与否。如果命令成功退出，那么退出状态为0，否则为非0.

➜   cat success_test.sh 
#!/bin/bash
#file name: success_test.sh
#对命令行参数求值，比如 success_test.sh `ls | grep txt`
echo "parameter is :"$@

eval $@

if [ $? -eq 0 ];
then 
    echo "$CMD executed successfully."
else
    echo "$CMD terminated unsuccessfully."
fi

执行：

➜   success_test.sh 'ls'
parameter is :ls
certbot-auto	t1		t3		test.sh
success_test.sh	t2		test.jsonnet
 executed successfully.

4. 向命令传递参数

➜   cat showArgs.sh
#!/bin/bash

for i in `seq 1 $#`
do
echo $i is $1
shift
done

执行：

➜   showArgs.sh a b cc
1 is a
2 is b
3 is cc

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