Spark修煉之道（基礎篇）——Linux大資料開發基礎：第十二節：Shell程式設計入門（四)
本節主要內容
- shell指令碼除錯
- shell函式
- shell控制結構初步
1. shell指令碼除錯
當指令碼出錯時，需要對指令碼進行除錯，學會指令碼除錯是每個linux系統使用者必備技能。shell指令碼除錯無需任何額外的工具，只需要要在指令碼檔案前加-x選項即可，建立debug.sh檔案，內容如下：
<code class="hljs bash has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-shebang" style="color: rgb(0, 102, 102); box-sizing: border-box;">#!/bin/bash</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#Filename: debug.sh</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"scripting"</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"debuging"</span> ls + </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>
使用bash -x 命令進行指令碼除錯
<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># bash -x debug.sh </span> + echo scripting scripting + echo debuging debuging + ls + <span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">ls:</span> cannot access +<span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:</span> <span class="hljs-constant" style="box-sizing: border-box;">No</span> such file <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">or</span> directory </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>
-x選項將shell指令碼每一行命令及執行結果列印輸出，如此便能幫助開發人員快速定位到出錯的指令碼位置。如果程式碼量比較大或者指令碼開發人員知道程式碼出錯的大致位置，則可以使用set -x; set +x；命令進行區域性除錯，如
<code class="hljs bash has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-shebang" style="color: rgb(0, 102, 102); box-sizing: border-box;">#!/bin/bash</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#Filename: debug2.sh</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> i <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> {<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>..<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> -x
//<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> -x表示跟在該命令後的指令碼輸出除錯資訊
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$i</span>
//<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x表示從此處禁用除錯
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">done</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Script executed"</span>
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>
上面的程式碼意味著，只會列印輸出echo $i，具體除錯資訊輸出如下：
<code class="hljs bash has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">root@sparkslave02:~/ShellLearning/Chapter12<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ./debug2.sh </span> + <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x + <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x + <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span> + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x + <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span> + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x + <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span> + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x + <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span> + <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li></ul>
除bash -x命令進行指令碼除錯之外，還可以在指令碼的第一行新增-xv命令，使得指令碼預設進行除錯，例如：
<code class="hljs bash has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//加-xv選項，使指令碼執行時會列印輸出除錯資訊
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#!/bin/bash -xv</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#Filename: debug.sh</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> i <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> {<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>..<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> -x
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$i</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> +x
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">done</span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Script executed"</span>
~ </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>
2. shell函式
同樣，同c、c ++等程式語言一樣，shell中可以定義函式，函式的定義格式如下
<code class="hljs matlab has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> <span class="hljs-title" style="box-sizing: border-box;">fname</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span></span>
<span class="hljs-cell" style="box-sizing: border-box;">{
shell指令碼語句；
}</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>
vim命令建立functionDemo.sh指令碼檔案
<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># vim functionDemo.sh</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#定義一個函式fname</span>
function fname(){
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#輸出第一個引數</span>
echo <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$1</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#輸出函式所在檔名</span>
echo <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$0</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#輸出所有引數</span>
echo <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$@</span>
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#將函式中傳入兩個引數</span>
fname <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"arg1"</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"args"</span>
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li></ul>
執行結果：
<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ./functionDemo.sh </span> arg1 ./functionDemo.sh arg1 args </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>
3. shell控制結構初步
同其它程式語言一樣，shell也有自己的控制結構，包括for迴圈、while迴圈、until迴圈，if語句等。本小節先介紹for迴圈的使用，for迴圈的用法非常多，下面給出四個最為常用的for迴圈用法
(1)for i in $(seq 10)
<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># vim forloop.sh</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> i <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$(</span>seq <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span> echo <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$i</span> done root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># chmod a+x forloop.sh </span> root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ./forloop.sh </span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">7</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">9</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span> </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li></ul>
(2) for((i=1;i<=10;i++))
<code class="hljs bash has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span>((i=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;i<=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>;i++)) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">echo</span> <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$i</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">done</span> </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>
(3)for i in ls
<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># vim forloop3.sh</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> i <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> `ls` <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span> echo <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$i</span> done root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># chmod a+x forloop3.sh</span> root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ./forloop3.sh </span> debug2.sh debug.sh forloop2.sh forloop3.sh forloop.sh functionDemo.sh </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li></ul>
(4)for i in ${arr[*]}
<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># vim forloop4.sh</span>
arr=(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> i <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">${</span>arr[*]}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">do</span>
echo <span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">${</span>arr[i]}
done
root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@sparkslave02</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:~/ShellLearning/Chapter12</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ./forloop4.sh </span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li></ul>轉載： http://blog.csdn.net/lovehuangjiaju/article/details/48914547
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