Things like this, my friend send me a package named qcon.zip with his Mac pc. I use ubuntu system,when I use the command to unzip the folder,I found something was wrong.I check the permission,and use another soft named 7z,but it can't work now. when i use the command unzip qcon.zip unzip qcon.zip -d test/ it returns me that: unzip: cannot find or open ”-O, ”-O.zip or ”-O.ZIP. So after install 7z,the command I use , Error: qcon.zip: Can not open file as archive --add the command file--- file qcon.zip it returns qcon.zip: Zip archive data, at least v1.0 to extract So,what can I do now,the folder permission is right.