shell for循环、循环变量值付给其他shell脚本的方法

2020-07-27 18:47:31

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

shell for 循环：

#!第一种写法 类似C、Javafor ((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）

1、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。

2、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，而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，类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。

3、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，并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/sha=mainecho "a is $a"echo "PID for parent before 2.sh:$$"case $1 in exec)  echo "using exec"  exec ./2.sh ;; *)  echo "using sourcing"  source ./2.sh ;;esacecho "PID FOR parent after 2.sh :$$"echo "now m"

#！2.sh#!/bin/shecho "PID FOR 2.SH:$$"echo "2.sh get a from main.sh is $a"a=2.shexport ab=3.shecho "now 2.sh a is $a"

执行结果：

a is mainPID for parent before 2.sh:1162using sourcingPID FOR 2.SH:11622.sh get a from main.sh is main`这里写代码片`now 2.sh a is 2.shPID FOR parent after 2.sh :1162now m

通过for循环，循环变量作为2.sh变量赋值并执行。

#！main主函数#!/bin/sha=0for ((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 1PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 1now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 2PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 2now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 3PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 3now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 4PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 4now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 5PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 5now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 6PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 6now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 7PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 7now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 8PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 8now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 9PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 9now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sha is 10PID for parent before 2.sh:1339using sourcingPID FOR 2.SH:13392.sh get a from main.sh is 10now 2.sh a is 2.shPID FOR parent after 2.sh :1339now a is 2.sh

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