File names on exFAT¶

Linux allows almost any character in a file name. exFAT, the filesystem Deucalion uses by default so that Windows and macOS can read the drive, does not. If you look at your backup with the Files app (or on Windows or a Mac), a few names look slightly different. Deucalion always restores the original names: the manifest remembers them.

What changes, and how¶

On your computer	On an exFAT drive	Why
`report: final?.txt`	`report： final？.txt`	`: * ? " < > \\|` and `\` are not allowed; they are replaced by look-alike characters.
`notes.txt` and `Notes.txt` in the same folder	`notes.txt` and `Notes (2).txt`	exFAT doesn't tell upper and lower case apart, so the second one gets a number.
`draft.` (ends with a dot)	`draft．`	exFAT drops dots and spaces at the end of a name.
`CON.txt`, `aux.log`	`CON＿.txt`, `aux＿.log`	Windows reserves these names.
A very long name	shortened, ending with `~` and a short code	exFAT allows at most 255 characters.

Here is the Documents folder of the demo backup, as stored on the drive:

$ ls "/media/alex/Alex Backup/Deucalion-Backup/home/Documents"
'Budget 2026.ods'   Notes.txt   Work        'report： final？.txt'    'Ταξίδι στην Κρήτη 🌍.md'
'CV - Alex.pdf'     Tax        'notes (2).txt'   Συνταγές.txt

And the same folder as Deucalion shows it, with the original names:

$ deucalion ls ~/Documents
  Budget 2026.ods  44.9 KB
  CV - Alex.pdf  177.7 KB
  notes.txt  31 B
  Notes.txt  39 B
  report: final?.txt  33 B
  Tax/  2 files, 116.2 KB
  Work/  2 files, 93.8 KB
  Συνταγές.txt  54 B
  Ταξίδι στην Κρήτη 🌍.md  34 B

Names in other alphabets and emoji (Συνταγές.txt, Ταξίδι στην Κρήτη 🌍.md) are fine on exFAT and stay exactly the same.

Linux-formatted drives keep names as they are

On a drive formatted for Linux only (ext4, which Deucalion uses inside LUKS-encrypted drives), nothing is renamed. The manifest is still written.

File names on exFAT¶

What changes, and how¶

Related¶