i already crated the directory name is “files” and set file permission 0777 for writable but can’t installation because system display message is “Errors occurred during installation: The directory specified for uploaded files does not exist or is not writable.” I don’t understand.
This is Directory for uploads = /home/www/virtual/mydomail.com/files and already set file permission is 0777 for writable.
there is a FAQ entry on file permission problems, which might be helpful.
Are you using the command line based installation or the webbased installation?
There is a difference here see step 5 of the installation docs.
Assuming you are using the web based installation.
Create a folder in a non web-accessible location and change the rights or better ownership of the directory to the user your webserver is running on (777 file permissions are not safe to use) like described in step 3 of the Installation docs
So this would be something like:
create the directory:
as superuser change the ownership to the user your web-server is running, if the user is www
chown www /path/to/some/non-web-accessible-directory
Here is an example to check the file permissions outside of OJS.
Hope this helps