julywhj的gravatar头像
julywhj2017-07-27 17:37:30
shell for循环、循环变量值付给其他shell脚本

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、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) 
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/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
now 2.sh a is 2.sh
PID FOR parent after 2.sh :1162
now 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/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

 

分享到:

最近浏览
136930880898月9日
最代码贡献等级说明
huoyong8月7日
最代码贡献等级说明
最代码官方 LV48月1日
最代码贡献等级说明
tanghao958月1日
最代码贡献等级说明
yincao8月1日
暂无贡献等级
yjx45100137月31日
最代码贡献等级说明
fellowfun7月30日
最代码贡献等级说明
Watson7月28日
最代码贡献等级说明
暂无贡献等级
随心Fly7月27日
最代码贡献等级说明
顶部客服微信二维码底部
>扫描二维码关注最代码为好友扫描二维码关注最代码为好友