扣丁学堂Linux培训简述shell for循环、循环变量值付给其余shell脚本的方法

本篇文章扣丁学堂Linux培训小编就为读者们分享一下shell for循环、循环变量值付给其余shell脚本的方法，对Linux开发技术感兴趣的小伙伴就随小编来了解一下吧，但愿对你们有所帮助。

本文主要将在shell中如何编写for循环，并将循环变量做为下个shell脚本的参数。

shell for 循环：

!第一种写法 相似C、Java

for ((i=1; i<=100; i ++))

do

echo $i

done

!第二种写法 in应用

for i in {1..100}

do

echo $i

done

!第三种写法 seq 使用

for i in seq 1 100

do

echo $i

done

将循环变量赋值到下一个脚本：

在运行shell脚本时候，有三种方式来调用外部的脚本，exec（exec script.sh）、source（source script.sh）、fork（./script.sh）

一、exec（exec /home/script.sh）：

使用exec来调用脚本，被执行的脚本会继承当前shell的环境变量。但事实上exec产生了新的进程，他会把主shell的进程资源占用并替换脚本内容，继承了原主shell的PID号，即原主shell剩下的内容不会执行。

二、source（source /home/script.sh）

使用source或者“.”来调用外部脚本，不会产生新的进程，继承当前shell环境变量，并且被调用的脚本运行结束后，它拥有的环境变量和声明变量会被当前shell保留，相似将调用脚本的内容复制过来直接执行。执行完毕后原主shell继续运行。

三、fork（/home/script.sh）

直接运行脚本，会以当前shell为父进程，产生新的进程，而且继承主脚本的环境变量和声明变量。执行完毕后，主脚本不会保留其环境变量和声明变量。

!main.sh主体

!/bin/sh

a=main

echo "a is $a"

echo "PID for parent before 2.sh:$$"

case $1 in

exec)

echo "using exec"

exec ./2.sh ;;

*)

echo "using sourcing"

source ./2.sh ;;

esac

echo "PID FOR parent after 2.sh :$$"

echo "now m"

！2.sh

!/bin/sh

echo "PID FOR 2.SH:$$"

echo "2.sh get a from main.sh is $a"

a=2.sh

export a

b=3.sh

echo "now 2.sh a is $a"

执行结果：

a is main

PID for parent before 2.sh:1162

using sourcing

PID FOR 2.SH:1162

2.sh get a from main.sh is main这里写代码片

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1162

now m

经过for循环，循环变量做为2.sh变量赋值并执行。

！main主函数

!/bin/sh

a=0

for ((i=1; i<=10; i ++))

do

a=$i

echo "a is $a"

echo "PID for parent before 2.sh:$$"

    echo "using sourcing"

    source ./2.sh

echo "PID FOR parent after 2.sh :$$"

echo "now a is $a"

done

输出结果：

a is 1

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 1

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 2

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 2

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 3

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 3

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 4

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 4

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 5

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 5

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 6

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 6

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 7

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 7

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 8

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 8

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 9

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 9

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

a is 10

PID for parent before 2.sh:1339

using sourcing

PID FOR 2.SH:1339

2.sh get a from main.sh is 10

now 2.sh a is 2.sh

PID FOR parent after 2.sh :1339

now a is 2.sh

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