php - Why is file uploaded into temp Directory first?

Question

When we upload a file using HTML Form it is uploaded to tmp folder on server first. After file uploading process is completed, We need to move the File to our folders using move_uploaded_file() function.

Why file is first uploaded on tmp folder? Why can't we upload the file to our destination folder directly?

Answer 1

如果文件未存储在临时目录中，则整个内容必须存储在内存中，直到脚本完成运行（或调用函数将其从内存中删除）。

给它一些大文件，服务器会耗尽内存，敲打交换分区并可能翻倒。