The error message “Please check for sufficient write file permissions” is generated by the Web-based downloader, known as Magento Connect Manager, which forms part of the Magento eCommerce platform. The Magento eCommerce platform is an open-source platform -- its source code can be downloaded, modified or distributed free of charge -- that is designed for online merchants.
Cause
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In order to use the Magento Connect Manager for installing, or upgrading, Magento software, you must have write permissions on all Magento files, including the main installation folder, or root folder. If you don’t, the Magento Connect Manager may generate the error message. To prevent the error message, you must add write permissions to the Magento root folder and all files and folders below the root folder. You can do this by entering the root folder and recursively changing the permissions on all the files and folders to “777.” Recursively means entering each folder you find below the root folder and changing the permissions on all the files and folders it contains and so on down the file system hierarchy to the bottom of the directory tree.
File Permissions
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Under the Unix operating system, file permissions are divided into three groups: “user,” “group” and “other.” Within each group, individual file permissions are represented by the letters r, w and x -- for “read,” “write” and “execute” -- or by the numbers 4, 2 and 1, in binary. The command “chmod 777 {filename}” changes the permissions on {filename} to read, write and execute for everyone.
Adding Write Permissions
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You can change the file permissions via a File Transfer Protocol (FTP) or Secure Shell (SSH) client. FTP is a software protocol for exchanging information between computers over a network, while SSH is a shell program for executing commands on a remote computer. To change file permissions via an SSH client, log in to your SSH account and type the following Unix commands:
cd
find . -type d -exec chmod 777 {} ;
chmod 666 downloader/config.ini
Removing Write Permissions
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Once you’ve changed the file permissions, you should be able to access the Magneto Connect Manager to complete the installation or upgrade you’re attempting. However, once you’ve completed the installation or upgrade, you need to remove the write permissions from the files and folders once again. To do this via SSH, type the following commands:
find . -type d -exec chmod 755 {} ;
find . -type f -exec chmod 644 {} ;
chmod o+w var media app/etc/use_cache.ser
Read more : http://www.ehow.com/info_12226902_error-please-check-sufficient-write-file-permissions.html