---
name: "translucency"
section: "8"
platform: "linux"
package: "translucency-source"
version: "0.6.0-3"
release: "Debian 3.1 (Sarge)"
platforms: ["linux"]
url: "https://new.carta.tech/translucency"
---

# translucency(8)

overlays file-systems

## NAME

translucency - overlays file-systems

## SYNOPSIS

**insmod translucency**

echo "/layer/1 -\> /layer/2" \> /proc/sys/translucency/0

\# alternatively, use mount.translucency

echo 65534 \> /proc/sys/translucency/uid

echo 16 \> /proc/sys/translucency/flags

## DESCRIPTION

**translucency** will install modified syscall handlers that redirect file operations in such a way as to logically merge several directories (presumably on different file-systems, on different media) into one directory.

## OPTIONS

Options can no longer be given at module loading time.  Instead they have to be written into the appropriate /proc/sys/translucency/\<option\> file.

- \[0-9\]\*

  are overlay entries used as seen above:  /layer/1 is lower layer - write access is redirected away. /layer/2 is upper layer - written files go here

- uid=\<int\>

  limits overlaying to user with EUID \<int\>

- gid=\<int\>

  limits overlaying to group with EGID \<int\>

- fs=\<int\>

  limits overlaying of mounts to filesystems with this magic number \<int\> ; negative values mean all except the given one ; for values see grep SUPER\_MAGIC /usr/include/linux/\*.h

- flags=\<int\>

  change the module's operation with a bitwise combination of the following:

  - 1=no\_translucency:

    turns module off

  - 2=no\_copyonwrite:

    kernel does not try to copy files if needed (i.e. for appending)

  - 4=no\_getdents:

    turn off merging directories - only entries in lower layer are shown in directory listings

  - 8=do\_downcase:

    downcase all filenames to avoid inconsistencies on case-insensitive filesystems

  - 16=no\_whiteout:

    do not automatically create whiteout entries which allow for renaming and deletion of files on r/o filesystems

## NOTES

This version requires /tmp to be writeable.

## KNOWN BUGS

Bad symlink handling

Bad .. handling after chdir into a dir that only exists in overlay

rmdir and rm -r are often not able to remove a directory stating that is not empty (it contains white-out entries)

There are probably serious buffer overflow conditions left in this module. Suggestions for improving the security of this module are welcome!

## BUGS

Report bugs through the bug-tracking system at http://sourceforge.net/projects/translucency/

## AUTHOR

Bernhard M. Wiedemann \<b.m.w@gmx.net\>

David Bird \<dbird@bpnetworks.com\>

## SEE ALSO

The effect is somewhat similar to: inheriting (ifs), stacking (fist), translucent (tfs), loopback (lofs), overlaying (ovlfs), and BSDs union file system

## VERSION

This manual page applies to translucency 0.6.0