Spark修炼之道（基础篇）——Linux大数据开发基础：第七节：进程管理

本节主要内容

1. 进程管理简介
2. 进程管理常用命令
3. 计划任务

1. 进程管理简介

（1）进程概念

进程是操作系统中非常重要的一个概念，进程是程序的执行过程，相对于程序，进程是动态的，在linux系统中，它与用户权限相关，程序与进程并没有一一对应，一个程序可能对应多个进程，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命令列出当前所有对应当前用户的活动进程</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> psxtwy<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;">//一个bash程序对应多个进程</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>

子进程与父进程：一个进程产生另外一个进程，产生的进程称为子进程，生成另外一个进程的进程称为父进程。

<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显示长格式进程信息</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//其中PID表示进程ID，PPID表示其父进程ID</span>xtwy<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@ubuntu</span>:~$ ps -lF 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）进程状态

进程状态总体来看主要包括三种，分别是就绪状态、运行状态、等待状态，就绪状态指的是进程除了CPU资源，其他运行资源都已获得，当就就绪状态的进程得到CPU资源时，则进入进程进入运行状态，运行状态的进程在时间片用完后会重新转换成就绪状态，如果在运行时进程遇到IO等阻塞操作，则进程会进入等待状态，等待状态的进程当阻塞操作完成后，进程将进入就绪状态 

上述三种进程状态还可以进一步细化，如下图： 

（3）前台进程与后台进程

前台进程指的是进程在执行时会将命令行阻塞，直到进程执行完毕；后台进程指的是进程在执行时不会阻塞当前命令行，而是在系统后台执行。

<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>，作为前台进程执行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&符号表示作为后台进程进行执行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. 进程管理常用命令

（1） ps命令

  ps 命令常用选项包括：  （1）a显示所有用户的进程  （2）u显示用户名和启动时间  （3）x显示所有进程，包括没有控制终端的进程  （4）e显示所有进程，包括没有控制终端的进程，较x选项，信息更为简略  （5）l显示进程详细信息，按长格式显示

下面给出几个演示： 
（1）ps -au 显示所有用户进程，并给出用户名和启动时间等详细信息

(2) ps -aux 显示所有用户进程，包括没有控制终端的进程，并给出用户和和启动埋单等详细信息 

<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;">输出格式中对应字段含义：<span class="hljs-label" style="box-sizing: border-box;">USER:</span> 进程所有者<span class="hljs-label" style="box-sizing: border-box;">PID:</span> 进程号%CPU: CPU占用率%MEM: 内存占用率VSZ：表示如果一个程序完全驻留在内存的话需要占用多少内存空间<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>RSS：指明了当前实际占用了多少内存<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> 终端的次要装置号码 (minor device number of tty)<span class="hljs-label" style="box-sizing: border-box;">STAT:</span> 该进程程的状态，有以下值<span class="hljs-label" style="box-sizing: border-box;">D:</span> 不可中断的静止<span class="hljs-label" style="box-sizing: border-box;">R:</span> 正在执行中<span class="hljs-label" style="box-sizing: border-box;">S:</span> 静止状态<span class="hljs-label" style="box-sizing: border-box;">T:</span> 暂停执行<span class="hljs-label" style="box-sizing: border-box;">Z:</span> 不存在但暂时无法消除<span class="hljs-label" style="box-sizing: border-box;">W:</span> 没有足够的记忆体分页可分配<: 高优先序的进程<span class="hljs-label" style="box-sizing: border-box;">N:</span> 低优先序的进程<span class="hljs-label" style="box-sizing: border-box;">L:</span> 有记忆体分页分配并锁在记忆体内<span class="hljs-label" style="box-sizing: border-box;">START:</span> 进程开始时间<span class="hljs-label" style="box-sizing: border-box;">TIME:</span> 执行的时间<span class="hljs-label" style="box-sizing: border-box;">COMMAND:</span>所执行的指令</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 按长格式显示进程详细信息 

<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;">输出格式对应字段含义：F 进程的标志, S 进程的状态, PID 进程的ID, PPID 进程的父进程ID,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">C</span> 进程的CPU占用率, PRI 进程的优先权,NI 进程的Nice值,ADDR 进程的地址空间,SZ 进程占用内存的大小,WCHAN 进程当前是否在运行,TTY 进程所属终端,Time 进程的运行时间,CMD 进程的命令.</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

有时候某个进程可能会长期占用CPU资源或无法正常执行或超出运行时间等，此时可能希望人工干预直接将进程杀死，这时候kill命令可以派上用场。

（1）kill pid，关闭进程 
有时间kill并不能保证一定会关闭某个进程，例如 
 
此时可以采用强制关闭的方式 
（2）kill -9 pid，强制关闭进程 
下面给出了强制进程的演示 

 
强制关闭进程后，终端强制退出 

（3） renice 修改进程的优先级

<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;">//重新指定权限</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;">//子进程的权限随父进程权限改变而改变</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） 进程的前台后台切换

（1）ctr+c命令终止进程 
ping baidu.com -a 命令将一直执行，终端被占用，要终止进程，需要使用ctr+c命令终止当前进程执行

<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>msrtt <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命令挂起进程

<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 -aroot<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命令将进程转到前台执行

<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命令将进程转到后台执行

<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命令查看任务

<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命令动态显示进程信息

top命令动态显示进程信息，可以对进程的CPU、内存使用情况进行动态监测 

（6） pstree显示进程树

将进程间的关系以树结构的形式展示

3. 计划任务的设定

（1） at命令安排作业在某一时刻执行一次

at命令指定时间的方式 
绝对计时方法： 
hh:mm MM/DD/YY 
相对计时方法： 
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>分钟后执行echo <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"hello"</span> > /home/xtwy/hellohello.txtxtwy@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> minuteswarning: 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;">//查看进程是否启动</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周期性运行作业

crontab 常用选项如下： 
-l 　　显示当前的crontab 
-r 　　删除当前的crontab 
-e 　　使用编辑器编辑当前crontab文件

<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;">采用crontab -e 命令进入计划任务编辑状态，时间及脚本设置格式如下：分钟 　　 小时　　 天 　　 月 　　 星期　　 命令/脚本例如在每周五下午<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">6</span>点关机，其命令设置如下：分钟　　 小时 　　 天　　 月　　  星期 　　 命令/脚本<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>显示当前的计划任务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>进入计划任务编辑状态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 oneSelect 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.tinyChoose <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>设置完成后再进行计划任务的查看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通过下面方式进行查看计划：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/cronxtwy<span class="hljs-property" style="box-sizing: border-box;">@ubuntu</span>:/<span class="hljs-reserved" style="box-sizing: border-box;">var</span>/spool/cron$ lsatjobs  atspool  crontabs<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">//</span>crontabs目录只有root用户才能查看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 deniedxtwy<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>xtwyroot<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> xtwyroot<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>

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