Simple interaction between PHP and server file system
php.ini中关于文件上传的设置指令
文件上传过程
（1）上传文件提交表单html代码：
<!--向服务器上传文件的HTML表单（限制为文本文件）--> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Adminstration - upoload new files</title> </head> <body> <h1>Upload new files</h1> <form action="upload.php" method="post" enctyple="multipart/form-data" > <!--enctyple:规定在发送到服务器之前对表单数据进行编码的方式（在上传控件时必须按照以上方式设置该属性）--> <div> <input type="hidden" name="MAX_FILE_SIZE" value="1000000"> <!--规定传输文件的最大字节数--> <label for="userfile">Upload a file</label> <!--在<label>内点击文本，会触发该控件，此时浏览器会自动对焦到标签for属性所指向的表单控件上面--> <input type="file" name="userfile" id="userfile"> <!--id属性为<label>标签for所指向控件元素的id号--> <input type="submit" value="Send File"> </div> </form> </body> </html>
（2）php处理上传文件代码
①在php脚本中，需要处理的数据保存在超级变量数组$_FILES中，开启register_globals指令可以直接通过变量名访问这些信息；
②假如表单变量名为“username“则有：
$_FILES['userfile']['tmp_name']：储存文件在Web服务器中的临时保存位置；
$_FILES['userfile']['name']：储存用户系统中文件的名称；
$_FILES['userfile']['size']：储存文件的大小；
$_FILES['userfile']['type']：储存文件的类型；
$_FILES['userfile']['error]：储存任何与文件上传相关的错误代码；
错误类型说明：
UPLOAD_ERR_INI_SIZE：1，上传的文件超过了 php.ini 中 upload_max_filesize 选项限制的值。
UPLOAD_ERR_FORM_SIZE：2，上传文件的大小超过了 HTML 表单中 MAX_FILE_SIZE 选项指定的值。
UPLOAD_ERR_PARTIAL：3，文件只有部分被上传。
UPLOAD_ERR_NO_FILE：4，没有文件被上传。
UPLOAD_ERR_NO_TMP_DIR：6，找不到临时文件夹。PHP 4.3.10 和 PHP 5.0.3 引进。
UPLOAD_ERR_CANT_WRITE：7，文件写入失败。PHP 5.1.0 引进。
③php代码
<?php
//检验文件传输异常
if($_FILES['userfile']['error']>0){
echo 'Problem';
switch($_FILES['userfile']['error']){
case 1: echo 'File exceeded upload_max_filesize';break;
case 2: echo 'File exceeded max_file_size';break;
case 3: echo 'File only partially upload';break;
case 4: echo 'No file uploaded';break;
case 6: echo 'Cannot upload file: No temp directory specified';break;
case 7: echo 'Upload failed:Cannot write to disk';break;
}
exit;
}
//检验传输的文件是否为文本文件
if($_FILES['userfile']['type'] != 'text/plain'){
echo 'Problem: file is not plain text';
exit;
}
//将上传文件包含在服务器中/uploads/的目录下（该目录必须独立于Web文档树）
$upfile = '/uploads/'.$_FILES['userfile']['name']; //在指定目录下以传输文件的文件名创建一个新文件
if(is_uploaded_file($_FILES['userfile']['tmp_name'])){
if(! move_uploaded_file($_FILES['userfile']['tmp_name'],$upfile)){ //将传输文件的临时文件移动到创建的新文件
echo 'Problem: Could not move file to destination directory';
exit;
}
}
else{
echo 'Problem: Possible file upload attack.Filename:';
echo $_FILES['username']['name'];
exit;
}
echo "File uploaded seuucessfully<br/><br/>";
//对传输文件清除html和php标记
$contents = file_get_contents($upfile); //将文件内容提取为一个字符串；
$contents = strip_tags($contents); //对该字符串擦除html和tags标记；
file_put_contents($_FILES['userfile']['name'],$contents); //将该字符串重新写入文件中；
//在浏览器上显示传输的文本文件内容
echo "<p>Preview of uploaded file contents:<br/><hr>>";
echo nl2br($contents);
echo "</br></hr>";3、使用目录函数
（1）从目录中读取文件名
①使用opendir（），readdir（），closedir（）函数；
<?php
$current_dir = '/uploads/'; //创建目录url对象
$dir = opendir($current_dir); //打开目录，结果返回一个目录对象
echo "<p>Upload directory is $current_dir</p>";
echo "<p>Directory Listing:</p><ul>";
while(($file = readdir($dir)) !== false){ //读取目录对象
if($file != "." && $file != ".."){ //过滤当前目录和上一级目录
echo "<li>$file</li>";
echo "<a href=\"filedetails.php?file=\'.$file.\'\">".$file."</a><br/>";
}
}
echo "</ul>";
closedir($dir); //关闭目录；
?>②使用php的dir类
<?php
$current_dir = '/uploads/'; //创建目录url对象
$dir = dir($current_dir); //创建dir对象
echo "<p>Handle is $dir->handle</p>";
echo "<p>Upload directory is $current_dir</p>";
echo "<p>Directory Listing:</p><ul>";
while(($file = $dir->read()) !== false){ //通过dir对象读取目录下的文件名
if($file != "." && $file != ".."){
echo "<li>$file</li>";
}
}
echo "</ul>";
$dir->close(); //关闭目录
?>（2）使用scandir（）函数对文本名称进行字母表的排序方式
<?php
$current_dir = '/uploads/'; //创建目录url对象
$files1 = scandir($current_dir); //将指定目录下的文件名保存为一个数组，默认以字母升序排序
$files2 = scandir($current_dir,1); //将指定目录下的文件名保存为一个数组，以字母降序排序
echo "<p>Upload directory is $current_dir</p>";
echo "<p>Directory Listing in alphabetical order,ascending:</p><ul>";
foreach($files1 as $file1) {
if($file1 != "." && $file1 != "..")
echo "<li>$file1</li>";
}
echo "</ul>";
?>（3）获取当前目录的其他信息
dirname（$path）：返回路径的目录部分；
basename($path)：返回路径的名称部分；
disk_free_space($path)：返回路径所在磁盘可以保存上传文件的容量；
（4）创建和删除目录
①mkdir（）：创建目录；
代码：
$oldumask = umask(0); //重置当前权限码
mkdir("/tmp/testing",0777); //创建目录
umask($oldumask); //恢复当前权限码②rmdir（）：删除目录;
代码：
rmdir("/temp/testing");
或rmdir("c:\\tmp\\testing');※要删除的目录必须是空目录；
4、与文件系统的交互
（1）获取文件信息：
while(($file = readdir($dir)) !== false){
echo "<a href=\"filedetails.php?file=\'.$file.\'\">".$file."</a><br/>";
}
<?php
$current_dir = '/uploads/';
$file = basename($file); //获取文件文件名
echo "<h1>Details of file</h1>";
echo "<h2>File data</h2>";
echo 'File last accessed: '.date('j F Y H:i',fileatime($file))."<br>"; //返回最近访问的时间戳
echo 'File last modifixed: '.date('j F Y H:i',filemtime($file))."<br>"; //返回最近修改的时间戳
$user = posix_getpwuid(fileowner($file)); //返回用户标识uid
echo 'File owner: '.$user['name']."<br/>";
$group = posix_getgrgid(filegroup($file)); //返回组织标识gid
echo 'File group: '.$group['name']."<br/>";
echo 'File permissions: '.decoct(fileperms($file))."<br/>"; //返回8位的权限码
echo 'File type'.filetype($file)."<br/>"; //返回文件类型
echo 'File size'.filesize($file)."<br/>"; //返回文件字节数
echo "<h2>File Tests</h2>";
echo 'is_dir?'.(is_dir($file) ? 'true':'false')."<br/>";
echo 'is_executable?'.(is_executable($file) ? 'true':'false')."<br/>"; //判断文件是否可执行；
echo 'is_file?'.(is_file($file) ? 'true':'false')."<br/>";
echo 'is_link?'.(is_link($file) ? 'true':'false')."<br/>";
echo 'is_readable?'.(is_readable($file) ? 'true':'false')."<br/>";
echo 'is_writable?'.(is_writable($file) ? 'true':'false')."<br/>";
?>（2）更改文件属性
chgrp(file,group)：修改文件的分组；
chmod(file,permissions)：修改文件的权限；
chown(file,user)：修改文件的所有者；
（3）创建、删除和移动文件
bool touch（$filename，[int time,[ int atime]]）：创建一个文件（time指定创建时间戳，atime指定可选时间戳）
unlink($filename)：删除一个文件
copy($source_path,$destination_path)：复制一个文件
rename($oldfile,$newfile)：重命名一个文件；
（4）使用程序执行函数
①String exec(String command[ ,array result [ ,int result_value]])
返回命名结果的最后一行，result变量可以返回字符组数，这些字符串代表输出的每一行，result_value获取返回代码；
②void passthru(String command[ ,int result_value])
结果直接输出到浏览器；
③String system(string command[ ,int return_value])
输出结果到浏览器，返回命令结果的最后一行或false；
※在用户提交的数据包括执行命令的一部分，应该进行以下包装：
system(escapeshellcmd($command));
5、与环境变量交互
phpinfo（）函数：获取php的所有变量列表；
getenv（"$key_name"）:
setenv("$key_name=$value");
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