(bash) How to find the max supported file-size of a filesystem?

bash, fat32, filesystems, fuse, linux

Solution

I think you can use `getconf /path` for this. Among the many sizes it prints there is also `FILESIZEBITS`. APUE says this about it:

minimum number of bits needed to represent, as a signed integer value, the maximum size of a regular file allowed in the specified directory

There is some concern that `getconf` does not return filesystem-specific information:

getconf isn't in principle capable of answering such a question because it's filesystem dependent.

That is not the case:

[cnicutar@lux ~]$ getconf FILESIZEBITS /some/fuseblk/mount
32

[cnicutar@lux ~]$ getconf FILESIZEBITS /
64

Problem

(bash) For a particular directory, I need to discover the maximum file size supported by that filesystem. The filesystem in question is probably mounted from external USB media, and might be FAT32, NTFS, exfat, or ext2. I know I could partially guess the information from `mount`, but I'd like a cleaner solution - plus in the case of exfat, `mount` shows the filesystem type as "fuseblk". (I am running Linux 3.2.0-4-686-pae #1 SMP Debian 3.2.51-1 i686 GNU/Linux) `getconf FILESIZEBITS path` does not work for a `fuseblk` mount of an exfat filesystem: it returns 32, which is inaccurate. So it is not a general solution.

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