Due to the limitations of the implementation of Web Server and PHP, it is difficult for us to use PHP to call some programs in Linux that require root permissions to execute in the real environment. To this, I found another way to bypass it from the Internet. this restriction. First, write a c program to transfer the system command, and then use PHP to execute the c program.
c program
First write a c file, such as /usr/local/ismole/w.c
<ol class="dp-c"> <li class="alt"><span><span class="comment">//note 由于wordpress编辑器的原因,请将此代码中头文件多余的空格去除 </span> </span></li> <li><span><span class="preprocessor">#include </span> </span></li> <li class="alt"><span><span class="preprocessor">#include </span> </span></li> <li><span><span class="preprocessor">#include </span> </span></li> <li class="alt"><span><span class="preprocessor">#include </span><span> </span></span></li> <li><span> </span></li> <li class="alt"> <span class="keyword">int</span><span> main() </span> </li> <li><span>{ </span></li> <li class="alt"><span> uid_t uid ,euid; </span></li> <li><span> </span></li> <li class="alt"> <span> </span><span class="comment">//note 获得当前的uid </span><span> </span> </li> <li><span> uid = getuid(); </span></li> <li class="alt"> <span> </span><span class="comment">//note 获得当前euid </span><span> </span> </li> <li><span> euid = geteuid(); </span></li> <li class="alt"><span> </span></li> <li> <span> </span><span class="comment">//note 交换这两个id </span><span> </span> </li> <li class="alt"> <span> </span><span class="keyword">if</span><span>(setreuid(euid, uid)) </span> </li> <li> <span> perror(</span><span class="string">"setreuid"</span><span>); </span> </li> <li class="alt"><span> </span></li> <li> <span> </span><span class="comment">//note 执行将要执行linux系统命令 </span><span> </span> </li> <li class="alt"> <span> system(</span><span class="string">"/usr/bin/w"</span><span>); </span> </li> <li> <span> </span><span class="keyword">return</span><span> 0; </span> </li> <li class="alt"><span>} </span></li> </ol>
//note Due to the WordPress editor, please remove the extra spaces from the header file in this code
Compile the file gcc -o ipt -Wall w.c, and the program w will be generated in the current directory.
Change the owner of this program chmod u+s ./w.
PHP execution
The content of the file is as follows. If placed in the web directory, the current server load will be output when accessed.
<ol class="dp-c"> <li class="alt"><span><span></span></span></li> <li> <span class="comment">//note key的验证过程 </span><span> </span> </li> <li class="alt"> <span class="keyword">if</span><span>(</span><span class="vars">$key</span><span> != </span><span class="vars">$authkey</span><span>) { </span> </li> <li> <span class="comment">// exit(key error); </span><span> </span> </li> <li class="alt"><span>} </span></li> <li><span> </span></li> <li class="alt"> <span class="vars">$last_line</span><span> = </span><span class="func">exec</span><span>(</span><span class="string">/usr/local/ismole/w</span><span>, </span><span class="vars">$retval</span><span>); </span> </li> <li><span> </span></li> <li class="alt"> <span class="vars">$returnArray</span><span> = </span><span class="func">explode</span><span>(</span><span class="string">"load average: "</span><span>, </span><span class="vars">$retval</span><span>[0]); </span> </li> <li> <span class="vars">$returnString</span><span> = </span><span class="vars">$returnArray</span><span>[1]; </span> </li> <li class="alt"><span> </span></li> <li> <span class="func">echo</span><span> </span><span class="vars">$returnString</span><span>; </span> </li> </ol>
According to the above example, we can use PHP to do any Linux system commands we want to execute, SVN updates, server monitoring, backup, recovery, daily maintenance, etc. For example, "Using SVN to build a test server"

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

Dreamweaver Mac version
Visual web development tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

Atom editor mac version download
The most popular open source editor

SublimeText3 Linux new version
SublimeText3 Linux latest version
