9.1.1. File System Structure

The location of all files and directories must comply with the Filesystem Hierarchy Standard (FHS), version 3.0, with the exceptions noted below, and except where doing so would violate other terms of Debian Policy. The following exceptions to the FHS apply:

1. The FHS requirement that architecture-independent application-specific static files be located in /usr/share is relaxed to a suggestion. In particular, a subdirectory of /usr/lib may be used by a package (or a collection of packages) to hold a mixture of architecture-independent and architecture-dependent files. However, when a directory is entirely composed of architecture-independent files, it should be located in /usr/share.

2. The optional rules related to user specific configuration files for applications are stored in the user’s home directory are relaxed. It is recommended that such files start with the ‘.’ character (a “dot file”), and if an application needs to create more than one dot file then the preferred placement is in a subdirectory with a name starting with a ‘.’ character, (a “dot directory”). In this case it is recommended the configuration files not start with the ‘.’ character.

3. Only the dynamic linker and libc are allowed to install files in /lib64.

4. The requirement for object files, internal binaries, and libraries, including libc.so.*, to be located directly under /lib{,32} and /usr/lib{,32} is amended, permitting files to instead be installed to /lib/triplet and /usr/lib/triplet, where triplet is the value returned by dpkg-architecture -qDEB_HOST_MULTIARCH for the architecture of the package. Packages may not install files to any triplet path other than the one matching the architecture of that package; for instance, an Architecture: amd64 package containing 32-bit x86 libraries may not install these libraries to /usr/lib/i386-linux-gnu. 1

   No package for a 64 bit architecture may install files in /usr/lib64/ or in a subdirectory of it.

   The requirement for C and C++ headers files to be accessible through the search path /usr/include/ is amended, permitting files to be accessible through the search path /usr/include/triplet where triplet is as above. 2

   Applications may also use a single subdirectory under /usr/lib/triplet.

   The execution time linker/loader, ld*, must still be made available in the existing location under /lib or /lib64 since this is part of the ELF ABI for the architecture.

5. The requirement that /usr/local/share/man be “synonymous” with /usr/local/man is relaxed to a recommendation

6. The requirement that window managers with a single configuration file call it system.*wmrc is removed, as is the restriction that the window manager subdirectory be named identically to the window manager name itself.

7. The requirement that boot manager configuration files live in /etc, or at least are symlinked there, is relaxed to a recommendation.

8. /var/run is required to be a symbolic link to /run, and /var/lock is required to be a symbolic link to /run/lock.

9. The /var/www directory is additionally allowed.

10. The requirement for /usr/local/share/color to exist if /usr/share/color exists is relaxed to a recommendation.

11. The requirement for /usr/local/libqual to exist if /libqual or /usr/libqual exists (where libqual is a variant of lib such as lib32 or lib64) is removed.

12. On GNU/Hurd systems, the following additional directories are allowed in the root filesystem: /hurd and /servers. 3

13. As an exception to the requirement for there to be no subdirectories in /usr/bin, the mh mail-handling suite may create /usr/bin/mh/, as was allowed in FHS version 2.3. Other subdirectories are not allowed.

The version of this document referred here can be found in the debian-policy package or on FHS (Debian copy) alongside this manual (or, if you have the debian-policy installed, you can try FHS (local copy)). The latest version, which may be a more recent version, may be found on FHS (upstream). Specific questions about following the standard may be asked on the debian-devel mailing list, or referred to the FHS mailing list (see the FHS web site for more information).