zoukankan      html  css  js  c++  java
  • shell脚本,awk常见初始化变量的题目。

    文件 内容如下 

    clone=line1
    gb=line1
    gi=line1
    lib=line1
    gb=line2
    gi=line2
    lib=line2
    clone=line3
    gb=line3
    gi=line3
    lib=line3
    gb=line4
    gi=line4
    lib=line4

    如何变为下面的内容

    lib=line1 gi=line1 gb=line1 clone=line1 
    lib=line2 gi=line2 gb=line2 
    lib=line3 gi=line3 gb=line3 clone=line3 
    lib=line4 gi=line4 gb=line4 

    [root@localhost 09-30]# cat file
    clone=line1
    gb=line1
    gi=line1
    lib=line1
    gb=line2
    gi=line2
    lib=line2
    clone=line3
    gb=line3
    gi=line3
    lib=line3
    gb=line4
    gi=line4
    lib=line4
    [root@localhost 09-30]# awk '{a=$0" "a}/^lib/{print a;a=""}' file
    lib=line1 gi=line1 gb=line1 clone=line1
    lib=line2 gi=line2 gb=line2
    lib=line3 gi=line3 gb=line3 clone=line3
    lib=line4 gi=line4 gb=line4
    [root@localhost 09-30]# awk '{a=$0" "a}/^lib/{print a}' file
    lib=line1 gi=line1 gb=line1 clone=line1
    lib=line2 gi=line2 gb=line2 lib=line1 gi=line1 gb=line1 clone=line1
    lib=line3 gi=line3 gb=line3 clone=line3 lib=line2 gi=line2 gb=line2 lib=line1 gi=line1 gb=line1 clone=line1
    lib=line4 gi=line4 gb=line4 lib=line3 gi=line3 gb=line3 clone=line3 lib=line2 gi=line2 gb=line2 lib=line1 gi=line1 gb=line1 clone=line1
    [root@localhost 09-30]#

    解题思路:awk '{a=$0" "a}/^lib/{print a;a=""}' file

    上面的结果是这个地方输出的 {a=$0" "a},这个结果只是循环进行赋值,当碰到^lib开头才进行输出 a的值 ,print a;a=""   第一个a是上面循环输出的值,最后的a是把变量a重新初始化变量,为什么要初始化是因为下一次要用这个变量的时候,不能因为之前这个变量有值,影响下一次用,好让它继续下次的循环赋值。

  • 相关阅读:
    很多网络库介绍
    CFileFind
    C#编写COM组件
    使用javascript调用com组件
    C++ 解析Json——jsoncpp
    休眠与开机自动运行等VC代码
    win7 vs2012/2013 编译boost 1.55
    VC中的字符串转换宏
    InstallShield 静默安装
    CAD版本 注册表信息
  • 原文地址:https://www.cnblogs.com/wangyuebo/p/5925266.html
Copyright © 2011-2022 走看看