在LAMP环境中，测试一个简单的PHP文件上传功能时，发现/var/log/apache2/中出现如下php警告：
[Tue Jan 31 09:40:27 2012] [error] [client ] PHP Warning: move_uploaded_file(/home/leotody/32883679.jpeg): failed to open stream: Permission denied in /var/www/upload_ on line 25, referer: http://localhost/
[Tue Jan 31 09:40:27 2012] [error] [client ] PHP Warning: move_uploaded_file(): Unable to move '/tmp/phps05ssU' to '/home/leotody/32883679.jpeg'in /var/www/upload_ on line 25, referer: http://localhost/
提示没有访问权限，文件上传的代码如下：
if (file_exists("upload/" . $_FILES["file"]["name"]))
{
echo $_FILES["file"]["name"] . " already exists. ";
}
else
{
if(move_uploaded_file($_FILES["file"]["tmp_name"], "upload/".$_FILES["file"]["name"]))
{
echo "Stored in: " . "upload/" . $_FILES["file"]["name"];
}
else
{
echo "move error!";
}
}
页面中显示"move error!"，说明move_uploaded_file()函数执行失败。
通过查找资料，发现网上有说是selinux启动的.原因，检查系统并未启动selinux，查看upload目录默认权限ls -ld upload，结果为755：
drwxr-xr-x 2 root root 4096 2012-01-31 10:59 upload
将upload目录权限改为777,sudo chmod 777 upload，再测试上传功能成功。但这种修改权限的方法并不安全。
故可以改upload目录的拥有者为www-data(即apache)，sudo chown -R www-data:www-data upload，然后再测试上传功能成功。
drwxr-xr-x 2 www-data www-data 4096 2012-01-31 10:59 upload
