ubuntu 11 - if-for-while-参数处理-sh

We believe that writing is about content, about what you want to say – not about fancy formatting.
我们坚信写作写的是内容，所思所想，而不是花样格式。
— Ulysses for Mac

直接看图

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第一种 for :

for NAME [in WORDS ... ] ; do COMMANDS; done

例如：

for a in 1 2 3 4 ; do echo $a ; done

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---

for a in 1 2 3 ; do echo $a > ${a}.txt ; done

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---

for a in 1 2 3 ; do rm ${a}.txt ; done

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if + for shell 编程

#!/bin/bash
if [[ $# -lt 1 ]] ; then echo no param !!! ; exit ; fi
for a in "$@" ; do echo $a > ${a} ; done

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for 语法二：

for (( exp1; exp2; exp3 )); do COMMANDS; done

例：

for (( a = 1 ; a < 11 ; a = a + 1 )) ; do echo $a ; done

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help while

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$# 是取得参数的个数
$1 是取第一个参数

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