Mount /system and /data partition of an android phone in Windows/Linux How can I mount the /system and /data partition of an Android Phone via USB on a computer? It will need to work with Windows and Linux. I have a Samsung Galaxy S4 with CyanogenMod 12 and working ADB.

PS: I want to have it mounted in a file manager and not in the terminal.
There is a method that I'm aware of which uses FTP on Android and a tool/software on Linux/Windows. I recently tested this method and it worked well. 


Host an FTP server on your Android phone. (There are answers for it on this site; you may use search option.)
On GNU/Linux, download curlftpfs and issue the command: 

curlftpfs ftp_server_url directory_path


where, ftp_server_url -> the URL of your FTP server, directory_path -> the directory in your PC where you want to mount this server
On Windows, I've heard that NetDrive can mount an FTP server on Windows. I haven't used it but got to know this from a ServerFault answer.
For Windows, if FTP doesn't work then host a WebDAV server on Android and mount it on Windows by using Windows native Map network drive feature.


Whether you would be able to write into /system and /data isn't my business here since you've not explicitly mentioned it, but my answer will definitely do the thins you asked in the question. :)

(Kindly let me know any fault in my answer rather than downvoting it, if you may. :) )