Linux example tool to change a mounted FAT filesystem partition's label while it is being used. Want a USB Stick's name to be writable? Then this might be for you.

dosfstools' fatlabel program writes this label too, so what's the difference? Well, it only write the label when the partition is unmounted or while created. fatattr_label simply makes the label writeable while the partition is being used.

./autogen.sh	make 

Run ./fatattr_label without parameters to see how to use it. This should look like so

Change label: fatattr_label [mountpoint] [label]	Show label: fatattr_label [mountpoint]	An example for listing available filesystems and their	mountpoints would be: df --output=source,fstype,target | grep -E 'msdos|fat' 

vfat, msdos and fat types are supported. You can of course make install it.

This tool is using the following ioctl interface that is not part of mainline Linux as of now:

 #define VFAT_IOCTL_SET_LABEL _IOW('r', 0x14, __u32) 

FAT12, FAT16 and FAT32 are supported, on 32bit and 64bit systems. You need to apply the provided patch and build your kernel. The patch is included in this source repository and applies to the latest Linux release.

I promised not to publish this quite yet. If you are overly interested in having support for this now, feel free to contact me.