SSHFS on OS X via Fuse and the Horrible Dot Underscore Turd Files

Once again, I have been issued a Mac to do development work, and as usual everything unixish on OS X almost works. To my delight, when faced with having to code against a Linux environment that I access via SSH, I found that since I last faced this situation, someone had made and is maintaining a port of Fuse for OS X with easy support for SSHFS. This discovery was a really great way to start the morning. I downloaded the installers, ran them, wrote my script to mount my remote machine to my filesystem, and had it working by the time I finished my first cup of coffee. Kudos to the team who maintain that port!

Of course, with the OS X filesystem in the mix, network attached filesystems never just work the way you want them to. In this case, the problem I ran into was the presence of files beginning with ._ the moment I created a new file in my repository and ran git status. I’ve seen these before. They pollute the files of most every filesystem ever touched remotely by a Mac, and they are totally invisible to the Mac user. They are used to store metadata for OS X, and are totally useless for any other computer. One Stack Overflow commenter deemed these dot underscore files “turd files”, which I consider an apt description. Apple calls the double underscore files “Apple Double” files. Whatever you want to call them, when being introduced into a client’s code repository on a Linux OS, these files beginning with ._ are turds and I want to prevent them from ever being created on my remote system.

It took some digging using a brand-name search engine, the name of which I will not disclose, but I was eventually directed back to the OSXFuse documentation, which, with a little reading, gave me a solution. (Cheers to working documentation!)

In the SSHFS connection string there are several options that can impact the creation of Apple Double (._) files. The two that I wound up using were noapplexattr and noappledouble. noapplexattr prevents OSX from even attempting to apply its extended attribute shenanigans to the SSHFS mounted operating system and noappledouble explicitly prevents the creation of any file beginning with a dot underscore as well as the also very annoying .DS_Store file. I’m not certain that both options were needed for my situation, but I used both and tested the result, and it seems to be working. Not almost working, just working.

My command for mounting my SSHFS looks like this (with sensitive bits redacted, of course):

sudo sshfs -o allow_other,defer_permissions,noapplexattr,noappledouble,IdentityFile=~/.ssh/id_rsa myusername@clientsserverhostname:/home/myusername /mnt/sshfs/mymountpoint

So long ._ files!

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