Spark修煉之道（基礎篇）——Linux大資料開發基礎：第七節：程式管理

五柳-先生發表於2015-11-14

本節主要內容

程式管理簡介
程式管理常用命令
計劃任務

1. 程式管理簡介

（1）程式概念

程式是作業系統中非常重要的一個概念，程式是程式的執行過程，相對於程式，程式是動態的，在linux系統中，它與使用者許可權相關，程式與程式並沒有一一對應，一個程式可能對應多個程式，例如：

<code class="hljs java 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-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//ps命令列出當前所有對應當前使用者的活動程式</span>
xtwy<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@ubuntu</span>:~$ ps
  PID TTY          TIME CMD
 <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2087</span> pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> bash
 <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2105</span> pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> ps
xtwy<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@ubuntu</span>:~$ bash
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//一個bash程式對應多個程式</span>
xtwy<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@ubuntu</span>:~$ ps
  PID TTY          TIME CMD
 <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2087</span> pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> bash
 <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2141</span> pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> bash
 <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2156</span> pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> ps
</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>

子程式與父程式：一個程式產生另外一個程式，產生的程式稱為子程式，生成另外一個程式的程式稱為父程式。

<code class="hljs java 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-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//ps -l顯示長格式程式資訊</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//其中PID表示程式ID，PPID表示其父程式ID</span>
xtwy<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@ubuntu</span>:~$ ps -l
F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> S  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1000</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2087</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2085</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;">80</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;">1443</span> wait   pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> bash
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> S  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1000</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2141</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2087</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;">80</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;">1443</span> wait   pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> bash
</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></ul>

（2）程式狀態

程式狀態總體來看主要包括三種，分別是就緒狀態、執行狀態、等待狀態，就緒狀態指的是程式除了CPU資源，其他執行資源都已獲得，當就就緒狀態的程式得到CPU資源時，則進入程式進入執行狀態，執行狀態的程式在時間片用完後會重新轉換成就緒狀態，如果在執行時程式遇到IO等阻塞操作，則程式會進入等待狀態，等待狀態的程式當阻塞操作完成後，程式將進入就緒狀態
這裡寫圖片描述

上述三種程式狀態還可以進一步細化，如下圖：
這裡寫圖片描述

（3）前臺程式與後臺程式

前臺程式指的是程式在執行時會將命令列阻塞，直到程式執行完畢；後臺程式指的是程式在執行時不會阻塞當前命令列，而是在系統後臺執行。

<code class="hljs avrasm 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;">//直接<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">ping</span>，作為前臺程式執行
root@ubuntu:~<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;"># ping www.baidu.com </span>
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">PING</span> www<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.a</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.shifen</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.com</span> (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">115.239</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.211</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.112</span>) <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">56</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">84</span>) bytes of data.
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">64</span> bytes from <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">115.239</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.211</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.112</span>: icmp_seq=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> ttl=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">128</span> time=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4.50</span> ms

//加&符號表示作為後臺程式進行執行
root@ubuntu:~<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;"># ping www.baidu.com -a &</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;">13330</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></ul>

2. 程式管理常用命令

（1） ps命令

  ps 命令常用選項包括：
  （1）a顯示所有使用者的程式
  （2）u顯示使用者名稱和啟動時間
  （3）x顯示所有程式，包括沒有控制終端的程式
  （4）e顯示所有程式，包括沒有控制終端的程式，較x選項，資訊更為簡略
  （5）l顯示程式詳細資訊，按長格式顯示

下面給出幾個演示：
（1）ps -au 顯示所有使用者程式，並給出使用者名稱和啟動時間等詳細資訊

這裡寫圖片描述

(2) ps -aux 顯示所有使用者程式，包括沒有控制終端的程式，並給出使用者和和啟動埋單等詳細資訊
這裡寫圖片描述

<code class="hljs avrasm 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;">輸出格式中對應欄位含義：
<span class="hljs-label" style="box-sizing: border-box;">USER:</span> 程式所有者
<span class="hljs-label" style="box-sizing: border-box;">PID:</span> 程式號
%CPU: CPU佔用率
%MEM: 記憶體佔用率
VSZ：表示如果一個程式完全駐留在記憶體的話需要佔用多少記憶體空間<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
RSS：指明瞭當前實際佔用了多少記憶體<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
<span class="hljs-label" style="box-sizing: border-box;">TTY:</span> 終端的次要裝置號碼 (minor device number of tty)
<span class="hljs-label" style="box-sizing: border-box;">STAT:</span> 該程式程的狀態，有以下值
<span class="hljs-label" style="box-sizing: border-box;">D:</span> 不可中斷的靜止
<span class="hljs-label" style="box-sizing: border-box;">R:</span> 正在執行中
<span class="hljs-label" style="box-sizing: border-box;">S:</span> 靜止狀態
<span class="hljs-label" style="box-sizing: border-box;">T:</span> 暫停執行
<span class="hljs-label" style="box-sizing: border-box;">Z:</span> 不存在但暫時無法消除
<span class="hljs-label" style="box-sizing: border-box;">W:</span> 沒有足夠的記憶體分頁可分配
<: 高優先序的程式
<span class="hljs-label" style="box-sizing: border-box;">N:</span> 低優先序的程式
<span class="hljs-label" style="box-sizing: border-box;">L:</span> 有記憶體分頁分配並鎖在記憶體內
<span class="hljs-label" style="box-sizing: border-box;">START:</span> 程式開始時間
<span class="hljs-label" style="box-sizing: border-box;">TIME:</span> 執行的時間
<span class="hljs-label" style="box-sizing: border-box;">COMMAND:</span>所執行的指令</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><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul>

(3) ps -l 按長格式顯示程式詳細資訊
這裡寫圖片描述

<code class="hljs mathematica 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;">輸出格式對應欄位含義：
F 程式的標誌, 
S 程式的狀態, 
PID 程式的ID, 
PPID 程式的父程式ID,
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">C</span> 程式的CPU佔用率, 
PRI 程式的優先權,
NI 程式的Nice值,
ADDR 程式的地址空間,
SZ 程式佔用記憶體的大小,
WCHAN 程式當前是否在執行,
TTY 程式所屬終端,
Time 程式的執行時間,
CMD 程式的命令.</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>

（2） kill 命令

有時候某個程式可能會長期佔用CPU資源或無法正常執行或超出執行時間等，此時可能希望人工干預直接將程式殺死，這時候kill命令可以派上用場。

（1）kill pid，關閉程式
有時間kill並不能保證一定會關閉某個程式，例如
這裡寫圖片描述
此時可以採用強制關閉的方式
（2）kill -9 pid，強制關閉程式
下面給出了強制程式的演示

這裡寫圖片描述
強制關閉程式後，終端強制退出

（3） renice 修改程式的優先順序

<code class="hljs livecodeserver 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@ubuntu:/home/xtwy<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ps -l</span>
F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span> S     <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;">12331</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12306</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;">99</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">19</span> -  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1120</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">wait</span>   pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> su
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> S     <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;">12340</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12331</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;">99</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">19</span> -  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1144</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">wait</span>   pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> bash
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span> R     <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;">12368</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12340</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;">99</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">19</span> -   <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">625</span> -      pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> ps<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">
//重新指定許可權</span>
root@ubuntu:/home/xtwy<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># renice -5 12340</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12340</span>: old priority <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">19</span>, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">new</span> priority -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">
//子程式的許可權隨父程式許可權改變而改變</span>
root@ubuntu:/home/xtwy<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ps -l</span>
F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span> S     <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;">12331</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12306</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;">99</span>  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">19</span> -  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1120</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">wait</span>   pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> su
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> S     <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;">12340</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12331</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;">75</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;">1144</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">wait</span>   pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> bash
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span> R     <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;">12373</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12340</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;">75</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;">625</span> -      pts/<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;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> ps
</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）程式的前臺後臺切換

（1）ctr+c命令終止程式
ping baidu.com -a 命令將一直執行，終端被佔用，要終止程式，需要使用ctr+c命令終止當前程式執行

<code class="hljs livecodeserver 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@ubuntu:/home/xtwy<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ping baidu.com -a </span>
PING baidu.com (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180.149</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.132</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.47</span>) <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">56</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">84</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">bytes</span> <span class="hljs-operator" style="box-sizing: border-box;">of</span> data.

^C64 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">bytes</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">from</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180.149</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.132</span><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.47</span>: icmp_seq=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> ttl=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">128</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">time</span>=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">138</span> ms

<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--- baidu.com ping statistics ---</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> packets transmitted, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> received, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>% packet loss, <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">time</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>ms
rtt <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">min</span>/<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">avg</span>/<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">max</span>/mdev = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">138.291</span>/<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">138.291</span>/<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">138.291</span>/<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.000</span> ms
</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></ul>

（2）ctr+z命令掛起程式

<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;">@ubuntu</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:/home/xtwy</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ping baidu.com -a </span>
<span class="hljs-constant" style="box-sizing: border-box;">PING</span> baidu.com (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180.149</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">132.47</span>) <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">56</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">84</span>) bytes of data.
^<span class="hljs-constant" style="box-sizing: border-box;">Z</span>
[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]+  <span class="hljs-constant" style="box-sizing: border-box;">Stopped</span>                 ping baidu.com -a
root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@ubuntu</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:/home/xtwy</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># jobs</span>
[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]+  <span class="hljs-constant" style="box-sizing: border-box;">Stopped</span>                 ping baidu.com -a
</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></ul>

（3）fg命令將程式轉到前臺執行

<code class="hljs handlebars 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="xml" style="box-sizing: border-box;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">root</span>@<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ubuntu:</span>/<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">home</span>/<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xtwy</span># <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">fg</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ping</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">baidu.com</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">-a</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">64</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">bytes</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">from</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">180.149.132.47:</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">icmp_seq</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">2</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ttl</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">128</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">time</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">135</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ms</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">64</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">bytes</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">from</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">180.149.132.47:</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">icmp_seq</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">3</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ttl</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">128</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">time</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">139</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ms</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">64</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">bytes</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">from</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">180.149.132.47:</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">icmp_seq</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">4</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ttl</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">128</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">time</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">135</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ms</span>
^<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">Z</span>
[<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">1</span>]+  <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">Stopped</span>                 <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">ping</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">baidu.com</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">-a</span>
</span></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></ul>

(4) bg命令將程式轉到後臺執行

<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;">@ubuntu</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:/home/xtwy</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># bg</span>
[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]+ ping baidu.com -a &
root<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@ubuntu</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:/home/xtwy</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># 64 bytes from 180.149.132.47: icmp_seq=5 ttl=128 time=134 ms</span>
jobs64 bytes from <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180.149</span>.<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">132.47</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:</span> icmp_seq=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span> ttl=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">128</span> time=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">135</span> ms

[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]+  <span class="hljs-constant" style="box-sizing: border-box;">Running</span>                 ping baidu.com -a &
</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></ul>

（5）jobs命令檢視任務

<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;">@ubuntu</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:/home/xtwy</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># jobs</span>
[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>]+  <span class="hljs-constant" style="box-sizing: border-box;">Running</span>                 ping baidu.com -a &</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></ul>

（5） top命令動態顯示程式資訊

top命令動態顯示程式資訊，可以對程式的CPU、記憶體使用情況進行動態監測
這裡寫圖片描述

（6） pstree顯示程式樹

將程式間的關係以樹結構的形式展示

這裡寫圖片描述

3. 計劃任務的設定

（1） at命令安排作業在某一時刻執行一次

at命令指定時間的方式
絕對計時方法：
hh:mm MM/DD/YY
相對計時方法：
now+n minutes
mow+n hours
now+n days

<code class="hljs livecodeserver 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-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>分鐘後執行echo <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"hello"</span> > /home/xtwy/hellohello.txt
xtwy@ubuntu:~$  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">at</span> now+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span> minutes
warning: commands will be executed <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">using</span> /bin/sh
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">at</span>> echo <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"hello"</span> > /home/xtwy/hellohello.txt
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">at</span>> <EOT>
job <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;">at</span> Tue Sep  <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;">07</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">21</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2015</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">
//檢視程式是否啟動</span>
xtwy@ubuntu:~$ <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">at</span> -l
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>   Tue Sep  <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;">07</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">21</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2015</span> <span class="hljs-operator" style="box-sizing: border-box;">a</span> xtwy
</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></ul>

（2）crontab週期性執行作業

crontab 常用選項如下：
-l 　　顯示當前的crontab
-r 　　刪除當前的crontab
-e 　　使用編輯器編輯當前crontab檔案

<code class="hljs coffeescript 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;">採用crontab -e 命令進入計劃任務編輯狀態，時間及指令碼設定格式如下：
分鐘 　　 小時　　 天 　　 月 　　 星期　　 命令/指令碼

例如在每週五下午<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>點關機，其命令設定如下：
分鐘　　 小時 　　 天　　 月　　  星期 　　 命令/指令碼
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00</span> 　　  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">18</span>　　    * 　　 * 　　 <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span> 　　 /usr/bin/shudown -h now

操作方法:
<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>顯示當前的計劃任務
xtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:~$ crontab -l
<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">no</span> crontab <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> xtwy

<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>進入計劃任務編輯狀態
xtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:~$ crontab -e 
<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">no</span> crontab <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> xtwy - using an empty one

Select an editor.  To change later, run <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'select-editor'</span>.
  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1.</span> /bin/ed
  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2.</span> /bin/nano        <---- easiest
  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3.</span> /usr/bin/vim.basic
  <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4.</span> /usr/bin/vim.tiny

Choose <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;">4</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-attribute" style="box-sizing: border-box; color: rgb(0, 136, 0);">crontab</span>: installing <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> crontab

<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>設定完成後再進行計劃任務的檢視
xtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:~$ crontab -l
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># m h  dom mon dow   command</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</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;">1</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span> echo <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"test crontab"</span> >> test.txt

通過下面方式進行檢視計劃：
xtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:~$ cd /<span class="hljs-reserved" style="box-sizing: border-box;">var</span>/spool/cron
xtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:/<span class="hljs-reserved" style="box-sizing: border-box;">var</span>/spool/cron$ ls
atjobs  atspool  crontabs
<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>crontabs目錄只有root使用者才能檢視
xtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/var/spool/cron$ cd crontabs/</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(0, 136, 0);">bash</span>: <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(0, 136, 0);">cd</span>: crontabs/: Permission denied
xtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:/<span class="hljs-reserved" style="box-sizing: border-box;">var</span>/spool/cron$ su root
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(0, 136, 0);">Password</span>: 
root<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/var/spool/cron# cd crontabs/</span>
root<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:/<span class="hljs-reserved" style="box-sizing: border-box;">var</span>/spool/cron/crontabs<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ls</span>
xtwy
root<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:/<span class="hljs-reserved" style="box-sizing: border-box;">var</span>/spool/cron/crontabs<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># ls -l</span>
total <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span>
-rw------- <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> xtwy crontab <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">275</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2015</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">09</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">01</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">17</span>:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">45</span> xtwy
root<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:/<span class="hljs-reserved" style="box-sizing: border-box;">var</span>/spool/cron/crontabs<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># cat xtwy </span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># DO NOT EDIT THIS FILE - edit the master and reinstall.</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># (/tmp/crontab.qUgCZF/crontab installed on Tue Sep  1 17:45:15 2015)</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># (Cron version -- $Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp $)</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"># m h  dom mon dow   command</span>
<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</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;">1</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span> echo <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"test crontab"</span> >> test.txt
</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><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li></ul>

轉載： http://blog.csdn.net/lovehuangjiaju/article/details/48049919