说明：  Linux下C实现TCP文件传输 使用说明 终端下输入 make 终端 就可以运行 服务端和客户端了 ./server ./client 功能说明 支持TCP文件传输模式 cmd 通道（TCP） list 显示当前目录所有文件名 cd 切换目录 put 上传 get 下载 data 通道（TCP/UDP) 同名文件覆盖 客户端和服务端的TCP文件传输，客户端可以上传文件到服务端，也可以从服务端下载文件，还可以查看和修改服务端的工作目录（临时）。
(TCP file transfer with C under Linux Instructions Input make under the terminal The terminal can run the server and the client. / server. / client Function description Supports TCP file transfer mode CMD channel (TCP) List displays all file names of the current directory CD switch directory Put upload Get Download Data channel (TCP / UDP) File overwrite with the same name TCP file transmission between the client and the server. The client can upload files to the server, download files from the server, and view and modify the working directory of the server (temporary).)