Without a doubt, Ricardo Galli’s WP-Cache is my favorite WordPress plugin. It speeds up WordPress significantly, therefore making your blog more appealing to your site vistitors.
You can either install WP-Cache like most plugins, by dropping it in your plugins folder: wp-content/plugins/. Or you can manually install which means you have to create a symbolic link from wp-content/advanced-cache.php to wp-content/plugins/wp-cache/wp-cache-phase1.php, something which is impossible to do if you do not have shell access to your hosting account. This is why I recommend the normal plugin install. However you still might have a problem with file permissions, which WordPress will warn you about once you go to Admin – Options – WP-Cache. Usually it will be due to something not being writeable, like:
You will need to change all three to permissions 0777. This still might result in an error with the symbolic link not creating. For this you must an FTP client like SmartFTP that allows you to change the stickybit. Depending on the ftp client you are using, this might show up as Stickybit or simply you will have a row of 4 boxes to type in a number. You will want to change the directories above to 7777, so that the symbolic link will create. This is usually the problem and solution, if you do not have shell access.
You can read a short description of Unix permissions on WebmasterWorld (membership required).
Once you get pass the permission issues, you should be able to view WP-Cache Options and configure the caching expire limit and exclude pages from caching. If you ever decide to remove WP-Cache and your site no longer works, you must manually go into wp-config and remove the define(“WP_CACHE”, true): line. For security reasons you should change the permissions of wp_config back to 644. Just remember to change the permissions on this file if you plan to enable or disable Wp-Cache.