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<title>Debian Policy Manual - The Operating System</title>

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<link href="ch-scope.html" rel="chapter" title="1 About this manual">
<link href="ch-archive.html" rel="chapter" title="2 The Debian Archive">
<link href="ch-binary.html" rel="chapter" title="3 Binary packages">
<link href="ch-source.html" rel="chapter" title="4 Source packages">
<link href="ch-controlfields.html" rel="chapter" title="5 Control files and their fields">
<link href="ch-maintainerscripts.html" rel="chapter" title="6 Package maintainer scripts and installation procedure">
<link href="ch-relationships.html" rel="chapter" title="7 Declaring relationships between packages">
<link href="ch-sharedlibs.html" rel="chapter" title="8 Shared libraries">
<link href="ch-opersys.html" rel="chapter" title="9 The Operating System">
<link href="ch-files.html" rel="chapter" title="10 Files">
<link href="ch-customized-programs.html" rel="chapter" title="11 Customized programs">
<link href="ch-docs.html" rel="chapter" title="12 Documentation">
<link href="ap-pkg-scope.html" rel="appendix" title="A Introduction and scope of these appendices">
<link href="ap-pkg-binarypkg.html" rel="appendix" title="B Binary packages (from old Packaging Manual)">
<link href="ap-pkg-sourcepkg.html" rel="appendix" title="C Source packages (from old Packaging Manual)">
<link href="ap-pkg-controlfields.html" rel="appendix" title="D Control files and their fields (from old Packaging Manual)">
<link href="ap-pkg-conffiles.html" rel="appendix" title="E Configuration file handling (from old Packaging Manual)">
<link href="ap-pkg-alternatives.html" rel="appendix" title="F Alternative versions of an interface - update-alternatives (from old Packaging Manual)">
<link href="ap-pkg-diversions.html" rel="appendix" title="G Diversions - overriding a package's version of a file (from old Packaging Manual)">
<link href="ch-scope.html#s1.1" rel="section" title="1.1 Scope">
<link href="ch-scope.html#s1.2" rel="section" title="1.2 New versions of this document">
<link href="ch-scope.html#s-authors" rel="section" title="1.3 Authors and Maintainers">
<link href="ch-scope.html#s-related" rel="section" title="1.4 Related documents">
<link href="ch-scope.html#s-definitions" rel="section" title="1.5 Definitions">
<link href="ch-archive.html#s-dfsg" rel="section" title="2.1 The Debian Free Software Guidelines">
<link href="ch-archive.html#s-sections" rel="section" title="2.2 Archive areas">
<link href="ch-archive.html#s-pkgcopyright" rel="section" title="2.3 Copyright considerations">
<link href="ch-archive.html#s-subsections" rel="section" title="2.4 Sections">
<link href="ch-archive.html#s-priorities" rel="section" title="2.5 Priorities">
<link href="ch-binary.html#s3.1" rel="section" title="3.1 The package name">
<link href="ch-binary.html#s-versions" rel="section" title="3.2 The version of a package">
<link href="ch-binary.html#s-maintainer" rel="section" title="3.3 The maintainer of a package">
<link href="ch-binary.html#s-descriptions" rel="section" title="3.4 The description of a package">
<link href="ch-binary.html#s-dependencies" rel="section" title="3.5 Dependencies">
<link href="ch-binary.html#s-virtual_pkg" rel="section" title="3.6 Virtual packages">
<link href="ch-binary.html#s3.7" rel="section" title="3.7 Base system">
<link href="ch-binary.html#s3.8" rel="section" title="3.8 Essential packages">
<link href="ch-binary.html#s-maintscripts" rel="section" title="3.9 Maintainer Scripts">
<link href="ch-source.html#s-standardsversion" rel="section" title="4.1 Standards conformance">
<link href="ch-source.html#s-pkg-relations" rel="section" title="4.2 Package relationships">
<link href="ch-source.html#s4.3" rel="section" title="4.3 Changes to the upstream sources">
<link href="ch-source.html#s-dpkgchangelog" rel="section" title="4.4 Debian changelog: debian/changelog">
<link href="ch-source.html#s-dpkgcopyright" rel="section" title="4.5 Copyright: debian/copyright">
<link href="ch-source.html#s4.6" rel="section" title="4.6 Error trapping in makefiles">
<link href="ch-source.html#s-timestamps" rel="section" title="4.7 Time Stamps">
<link href="ch-source.html#s-restrictions" rel="section" title="4.8 Restrictions on objects in source packages">
<link href="ch-source.html#s-debianrules" rel="section" title="4.9 Main building script: debian/rules">
<link href="ch-source.html#s-substvars" rel="section" title="4.10 Variable substitutions: debian/substvars">
<link href="ch-source.html#s-debianwatch" rel="section" title="4.11 Optional upstream source location: debian/watch">
<link href="ch-source.html#s-debianfiles" rel="section" title="4.12 Generated files list: debian/files">
<link href="ch-source.html#s-embeddedfiles" rel="section" title="4.13 Convenience copies of code">
<link href="ch-source.html#s-readmesource" rel="section" title="4.14 Source package handling: debian/README.source">
<link href="ch-controlfields.html#s-controlsyntax" rel="section" title="5.1 Syntax of control files">
<link href="ch-controlfields.html#s-sourcecontrolfiles" rel="section" title="5.2 Source package control files -- debian/control">
<link href="ch-controlfields.html#s-binarycontrolfiles" rel="section" title="5.3 Binary package control files -- DEBIAN/control">
<link href="ch-controlfields.html#s-debiansourcecontrolfiles" rel="section" title="5.4 Debian source control files -- .dsc">
<link href="ch-controlfields.html#s-debianchangesfiles" rel="section" title="5.5 Debian changes files -- .changes">
<link href="ch-controlfields.html#s-controlfieldslist" rel="section" title="5.6 List of fields">
<link href="ch-controlfields.html#s5.7" rel="section" title="5.7 User-defined fields">
<link href="ch-maintainerscripts.html#s6.1" rel="section" title="6.1 Introduction to package maintainer scripts">
<link href="ch-maintainerscripts.html#s-idempotency" rel="section" title="6.2 Maintainer scripts idempotency">
<link href="ch-maintainerscripts.html#s-controllingterminal" rel="section" title="6.3 Controlling terminal for maintainer scripts">
<link href="ch-maintainerscripts.html#s-exitstatus" rel="section" title="6.4 Exit status">
<link href="ch-maintainerscripts.html#s-mscriptsinstact" rel="section" title="6.5 Summary of ways maintainer scripts are called">
<link href="ch-maintainerscripts.html#s-unpackphase" rel="section" title="6.6 Details of unpack phase of installation or upgrade">
<link href="ch-maintainerscripts.html#s-configdetails" rel="section" title="6.7 Details of configuration">
<link href="ch-maintainerscripts.html#s-removedetails" rel="section" title="6.8 Details of removal and/or configuration purging">
<link href="ch-relationships.html#s-depsyntax" rel="section" title="7.1 Syntax of relationship fields">
<link href="ch-relationships.html#s-binarydeps" rel="section" title="7.2 Binary Dependencies - Depends, Recommends, Suggests, Enhances, Pre-Depends">
<link href="ch-relationships.html#s-breaks" rel="section" title="7.3 Packages which break other packages - Breaks">
<link href="ch-relationships.html#s-conflicts" rel="section" title="7.4 Conflicting binary packages - Conflicts">
<link href="ch-relationships.html#s-virtual" rel="section" title="7.5 Virtual packages - Provides">
<link href="ch-relationships.html#s-replaces" rel="section" title="7.6 Overwriting files and replacing packages - Replaces">
<link href="ch-relationships.html#s-sourcebinarydeps" rel="section" title="7.7 Relationships between source and binary packages - Build-Depends, Build-Depends-Indep, Build-Conflicts, Build-Conflicts-Indep">
<link href="ch-sharedlibs.html#s-sharedlibs-runtime" rel="section" title="8.1 Run-time shared libraries">
<link href="ch-sharedlibs.html#s-sharedlibs-support-files" rel="section" title="8.2 Shared library support files">
<link href="ch-sharedlibs.html#s-sharedlibs-static" rel="section" title="8.3 Static libraries">
<link href="ch-sharedlibs.html#s-sharedlibs-dev" rel="section" title="8.4 Development files">
<link href="ch-sharedlibs.html#s-sharedlibs-intradeps" rel="section" title="8.5 Dependencies between the packages of the same library">
<link href="ch-sharedlibs.html#s-sharedlibs-shlibdeps" rel="section" title="8.6 Dependencies between the library and other packages - the shlibs system">
<link href="ch-opersys.html#s9.1" rel="section" title="9.1 File system hierarchy">
<link href="ch-opersys.html#s9.2" rel="section" title="9.2 Users and groups">
<link href="ch-opersys.html#s-sysvinit" rel="section" title="9.3 System run levels and init.d scripts">
<link href="ch-opersys.html#s9.4" rel="section" title="9.4 Console messages from init.d scripts">
<link href="ch-opersys.html#s-cron-jobs" rel="section" title="9.5 Cron jobs">
<link href="ch-opersys.html#s-menus" rel="section" title="9.6 Menus">
<link href="ch-opersys.html#s-mime" rel="section" title="9.7 Multimedia handlers">
<link href="ch-opersys.html#s9.8" rel="section" title="9.8 Keyboard configuration">
<link href="ch-opersys.html#s9.9" rel="section" title="9.9 Environment variables">
<link href="ch-opersys.html#s-doc-base" rel="section" title="9.10 Registering Documents using doc-base">
<link href="ch-files.html#s-binaries" rel="section" title="10.1 Binaries">
<link href="ch-files.html#s-libraries" rel="section" title="10.2 Libraries">
<link href="ch-files.html#s10.3" rel="section" title="10.3 Shared libraries">
<link href="ch-files.html#s-scripts" rel="section" title="10.4 Scripts">
<link href="ch-files.html#s10.5" rel="section" title="10.5 Symbolic links">
<link href="ch-files.html#s10.6" rel="section" title="10.6 Device files">
<link href="ch-files.html#s-config-files" rel="section" title="10.7 Configuration files">
<link href="ch-files.html#s10.8" rel="section" title="10.8 Log files">
<link href="ch-files.html#s-permissions-owners" rel="section" title="10.9 Permissions and owners">
<link href="ch-customized-programs.html#s-arch-spec" rel="section" title="11.1 Architecture specification strings">
<link href="ch-customized-programs.html#s11.2" rel="section" title="11.2 Daemons">
<link href="ch-customized-programs.html#s11.3" rel="section" title="11.3 Using pseudo-ttys and modifying wtmp, utmp and lastlog">
<link href="ch-customized-programs.html#s11.4" rel="section" title="11.4 Editors and pagers">
<link href="ch-customized-programs.html#s-web-appl" rel="section" title="11.5 Web servers and applications">
<link href="ch-customized-programs.html#s-mail-transport-agents" rel="section" title="11.6 Mail transport, delivery and user agents">
<link href="ch-customized-programs.html#s11.7" rel="section" title="11.7 News system configuration">
<link href="ch-customized-programs.html#s11.8" rel="section" title="11.8 Programs for the X Window System">
<link href="ch-customized-programs.html#s-perl" rel="section" title="11.9 Perl programs and modules">
<link href="ch-customized-programs.html#s-emacs" rel="section" title="11.10 Emacs lisp programs">
<link href="ch-customized-programs.html#s11.11" rel="section" title="11.11 Games">
<link href="ch-docs.html#s12.1" rel="section" title="12.1 Manual pages">
<link href="ch-docs.html#s12.2" rel="section" title="12.2 Info documents">
<link href="ch-docs.html#s12.3" rel="section" title="12.3 Additional documentation">
<link href="ch-docs.html#s12.4" rel="section" title="12.4 Preferred documentation formats">
<link href="ch-docs.html#s-copyrightfile" rel="section" title="12.5 Copyright information">
<link href="ch-docs.html#s12.6" rel="section" title="12.6 Examples">
<link href="ch-docs.html#s-changelogs" rel="section" title="12.7 Changelog files">
<link href="ap-pkg-binarypkg.html#s-pkg-bincreating" rel="section" title="B.1 Creating package files - dpkg-deb">
<link href="ap-pkg-binarypkg.html#s-pkg-controlarea" rel="section" title="B.2 Package control information files">
<link href="ap-pkg-binarypkg.html#s-pkg-controlfile" rel="section" title="B.3 The main control information file: control">
<link href="ap-pkg-binarypkg.html#sB.4" rel="section" title="B.4 Time Stamps">
<link href="ap-pkg-sourcepkg.html#s-pkg-sourcetools" rel="section" title="C.1 Tools for processing source packages">
<link href="ap-pkg-sourcepkg.html#s-pkg-sourcetree" rel="section" title="C.2 The Debian package source tree">
<link href="ap-pkg-sourcepkg.html#s-pkg-sourcearchives" rel="section" title="C.3 Source packages as archives">
<link href="ap-pkg-sourcepkg.html#sC.4" rel="section" title="C.4 Unpacking a Debian source package without dpkg-source">
<link href="ap-pkg-controlfields.html#sD.1" rel="section" title="D.1 Syntax of control files">
<link href="ap-pkg-controlfields.html#sD.2" rel="section" title="D.2 List of fields">
<link href="ap-pkg-conffiles.html#sE.1" rel="section" title="E.1 Automatic handling of configuration files by dpkg">
<link href="ap-pkg-conffiles.html#sE.2" rel="section" title="E.2 Fully-featured maintainer script configuration handling">
<link href="ch-archive.html#s-main" rel="subsection" title="2.2.1 The main archive area">
<link href="ch-archive.html#s-contrib" rel="subsection" title="2.2.2 The contrib archive area">
<link href="ch-archive.html#s-non-free" rel="subsection" title="2.2.3 The non-free archive area">
<link href="ch-binary.html#s3.2.1" rel="subsection" title="3.2.1 Version numbers based on dates">
<link href="ch-binary.html#s-synopsis" rel="subsection" title="3.4.1 The single line synopsis">
<link href="ch-binary.html#s-extendeddesc" rel="subsection" title="3.4.2 The extended description">
<link href="ch-binary.html#s-maintscriptprompt" rel="subsection" title="3.9.1 Prompting in maintainer scripts">
<link href="ch-source.html#s-debianrules-options" rel="subsection" title="4.9.1 debian/rules and DEB_BUILD_OPTIONS">
<link href="ch-controlfields.html#s-f-Source" rel="subsection" title="5.6.1 Source">
<link href="ch-controlfields.html#s-f-Maintainer" rel="subsection" title="5.6.2 Maintainer">
<link href="ch-controlfields.html#s-f-Uploaders" rel="subsection" title="5.6.3 Uploaders">
<link href="ch-controlfields.html#s-f-Changed-By" rel="subsection" title="5.6.4 Changed-By">
<link href="ch-controlfields.html#s-f-Section" rel="subsection" title="5.6.5 Section">
<link href="ch-controlfields.html#s-f-Priority" rel="subsection" title="5.6.6 Priority">
<link href="ch-controlfields.html#s-f-Package" rel="subsection" title="5.6.7 Package">
<link href="ch-controlfields.html#s-f-Architecture" rel="subsection" title="5.6.8 Architecture">
<link href="ch-controlfields.html#s-f-Essential" rel="subsection" title="5.6.9 Essential">
<link href="ch-controlfields.html#s5.6.10" rel="subsection" title="5.6.10 Package interrelationship fields: Depends, Pre-Depends, Recommends, Suggests, Breaks, Conflicts, Provides, Replaces, Enhances">
<link href="ch-controlfields.html#s-f-Standards-Version" rel="subsection" title="5.6.11 Standards-Version">
<link href="ch-controlfields.html#s-f-Version" rel="subsection" title="5.6.12 Version">
<link href="ch-controlfields.html#s-f-Description" rel="subsection" title="5.6.13 Description">
<link href="ch-controlfields.html#s-f-Distribution" rel="subsection" title="5.6.14 Distribution">
<link href="ch-controlfields.html#s-f-Date" rel="subsection" title="5.6.15 Date">
<link href="ch-controlfields.html#s-f-Format" rel="subsection" title="5.6.16 Format">
<link href="ch-controlfields.html#s-f-Urgency" rel="subsection" title="5.6.17 Urgency">
<link href="ch-controlfields.html#s-f-Changes" rel="subsection" title="5.6.18 Changes">
<link href="ch-controlfields.html#s-f-Binary" rel="subsection" title="5.6.19 Binary">
<link href="ch-controlfields.html#s-f-Installed-Size" rel="subsection" title="5.6.20 Installed-Size">
<link href="ch-controlfields.html#s-f-Files" rel="subsection" title="5.6.21 Files">
<link href="ch-controlfields.html#s-f-Closes" rel="subsection" title="5.6.22 Closes">
<link href="ch-controlfields.html#s-f-Homepage" rel="subsection" title="5.6.23 Homepage">
<link href="ch-controlfields.html#s-f-Checksums" rel="subsection" title="5.6.24 Checksums-Sha1 and Checksums-Sha256">
<link href="ch-controlfields.html#s-f-DM-Upload-Allowed" rel="subsection" title="5.6.25 DM-Upload-Allowed">
<link href="ch-relationships.html#s7.6.1" rel="subsection" title="7.6.1 Overwriting files in other packages">
<link href="ch-relationships.html#s7.6.2" rel="subsection" title="7.6.2 Replacing whole packages, forcing their removal">
<link href="ch-sharedlibs.html#s-ldconfig" rel="subsection" title="8.1.1 ldconfig">
<link href="ch-sharedlibs.html#s8.6.1" rel="subsection" title="8.6.1 The shlibs files present on the system">
<link href="ch-sharedlibs.html#s8.6.2" rel="subsection" title="8.6.2 How to use dpkg-shlibdeps and the shlibs files">
<link href="ch-sharedlibs.html#s-shlibs" rel="subsection" title="8.6.3 The shlibs File Format">
<link href="ch-sharedlibs.html#s8.6.4" rel="subsection" title="8.6.4 Providing a shlibs file">
<link href="ch-opersys.html#s-fhs" rel="subsection" title="9.1.1 File System Structure">
<link href="ch-opersys.html#s9.1.2" rel="subsection" title="9.1.2 Site-specific programs">
<link href="ch-opersys.html#s9.1.3" rel="subsection" title="9.1.3 The system-wide mail directory">
<link href="ch-opersys.html#s-fhs-run" rel="subsection" title="9.1.4 /run and /run/lock">
<link href="ch-opersys.html#s9.2.1" rel="subsection" title="9.2.1 Introduction">
<link href="ch-opersys.html#s9.2.2" rel="subsection" title="9.2.2 UID and GID classes">
<link href="ch-opersys.html#s-/etc/init.d" rel="subsection" title="9.3.1 Introduction">
<link href="ch-opersys.html#s-writing-init" rel="subsection" title="9.3.2 Writing the scripts">
<link href="ch-opersys.html#s9.3.3" rel="subsection" title="9.3.3 Interfacing with the initscript system">
<link href="ch-opersys.html#s9.3.3.1" rel="subsection" title="9.3.3.1 Managing the links">
<link href="ch-opersys.html#s9.3.3.2" rel="subsection" title="9.3.3.2 Running initscripts">
<link href="ch-opersys.html#s9.3.4" rel="subsection" title="9.3.4 Boot-time initialization">
<link href="ch-opersys.html#s9.3.5" rel="subsection" title="9.3.5 Example">
<link href="ch-opersys.html#s-cron-files" rel="subsection" title="9.5.1 Cron job file names">
<link href="ch-files.html#s10.7.1" rel="subsection" title="10.7.1 Definitions">
<link href="ch-files.html#s10.7.2" rel="subsection" title="10.7.2 Location">
<link href="ch-files.html#s10.7.3" rel="subsection" title="10.7.3 Behavior">
<link href="ch-files.html#s10.7.4" rel="subsection" title="10.7.4 Sharing configuration files">
<link href="ch-files.html#s10.7.5" rel="subsection" title="10.7.5 User configuration files (&quot;dotfiles&quot;)">
<link href="ch-files.html#s10.9.1" rel="subsection" title="10.9.1 The use of dpkg-statoverride">
<link href="ch-customized-programs.html#s-arch-wildcard-spec" rel="subsection" title="11.1.1 Architecture wildcards">
<link href="ch-customized-programs.html#s11.8.1" rel="subsection" title="11.8.1 Providing X support and package priorities">
<link href="ch-customized-programs.html#s11.8.2" rel="subsection" title="11.8.2 Packages providing an X server">
<link href="ch-customized-programs.html#s11.8.3" rel="subsection" title="11.8.3 Packages providing a terminal emulator">
<link href="ch-customized-programs.html#s11.8.4" rel="subsection" title="11.8.4 Packages providing a window manager">
<link href="ch-customized-programs.html#s11.8.5" rel="subsection" title="11.8.5 Packages providing fonts">
<link href="ch-customized-programs.html#s-appdefaults" rel="subsection" title="11.8.6 Application defaults files">
<link href="ch-customized-programs.html#s11.8.7" rel="subsection" title="11.8.7 Installation directory issues">
<link href="ch-docs.html#s-copyrightformat" rel="subsection" title="12.5.1 Machine-readable copyright information">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-source" rel="subsection" title="C.1.1 dpkg-source - packs and unpacks Debian source packages">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-buildpackage" rel="subsection" title="C.1.2 dpkg-buildpackage - overall package-building control script">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-gencontrol" rel="subsection" title="C.1.3 dpkg-gencontrol - generates binary package control files">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-shlibdeps" rel="subsection" title="C.1.4 dpkg-shlibdeps - calculates shared library dependencies">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-distaddfile" rel="subsection" title="C.1.5 dpkg-distaddfile - adds a file to debian/files">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-genchanges" rel="subsection" title="C.1.6 dpkg-genchanges - generates a .changes upload control file">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-parsechangelog" rel="subsection" title="C.1.7 dpkg-parsechangelog - produces parsed representation of a changelog">
<link href="ap-pkg-sourcepkg.html#s-pkg-dpkg-architecture" rel="subsection" title="C.1.8 dpkg-architecture - information about the build and host system">
<link href="ap-pkg-sourcepkg.html#s-pkg-debianrules" rel="subsection" title="C.2.1 debian/rules - the main building script">
<link href="ap-pkg-sourcepkg.html#s-pkg-srcsubstvars" rel="subsection" title="C.2.2 debian/substvars and variable substitutions">
<link href="ap-pkg-sourcepkg.html#sC.2.3" rel="subsection" title="C.2.3 debian/files">
<link href="ap-pkg-sourcepkg.html#sC.2.4" rel="subsection" title="C.2.4 debian/tmp">
<link href="ap-pkg-sourcepkg.html#sC.4.1" rel="subsection" title="C.4.1 Restrictions on objects in source packages">
<link href="ap-pkg-controlfields.html#s-pkg-f-Filename" rel="subsection" title="D.2.1 Filename and MSDOS-Filename">
<link href="ap-pkg-controlfields.html#s-pkg-f-Size" rel="subsection" title="D.2.2 Size and MD5sum">
<link href="ap-pkg-controlfields.html#s-pkg-f-Status" rel="subsection" title="D.2.3 Status">
<link href="ap-pkg-controlfields.html#s-pkg-f-Config-Version" rel="subsection" title="D.2.4 Config-Version">
<link href="ap-pkg-controlfields.html#s-pkg-f-Conffiles" rel="subsection" title="D.2.5 Conffiles">
<link href="ap-pkg-controlfields.html#sD.2.6" rel="subsection" title="D.2.6 Obsolete fields">

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</p>

<hr>

<h1>
Debian Policy Manual
<br>Chapter 9 - The Operating System
</h1>

<hr>

<h2><a name="s9.1"></a>9.1 File system hierarchy</h2>

<hr>

<h3><a name="s-fhs"></a>9.1.1 File System Structure</h3>

<p>
The location of all files and directories must comply with the Filesystem
Hierarchy Standard (FHS), version 2.3, with the exceptions noted below, and
except where doing so would violate other terms of Debian Policy.  The
following exceptions to the FHS apply:
</p>
<ol type="1" start="1" >
<li>
<p>
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 '<samp>.</samp>' character (a
&quot;dot file&quot;), 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 &quot;dot directory&quot;).  In this case it is
recommended the configuration files not start with the '.'  character.
</p>
</li>
</ol>
<ol type="1" start="2" >
<li>
<p>
The requirement for amd64 to use <code>/lib64</code> for 64 bit binaries is
removed.
</p>
</li>
</ol>
<ol type="1" start="3" >
<li>
<p>
The requirement for object files, internal binaries, and libraries, including
<code>libc.so.*</code>, to be located directly under <code>/lib{,32}</code> and
<code>/usr/lib{,32}</code> is amended, permitting files to instead be installed
to <code>/lib/<var>triplet</var></code> and
<code>/usr/lib/<var>triplet</var></code>, where <samp><var>triplet</var></samp>
is the value returned by <samp>dpkg-architecture -qDEB_HOST_MULTIARCH</samp>
for the architecture of the package.  Packages may <em>not</em> install files
to any <var>triplet</var> path other than the one matching the architecture of
that package; for instance, an <samp>Architecture: amd64</samp> package
containing 32-bit x86 libraries may not install these libraries to
<code>/usr/lib/i386-linux-gnu</code>.  [<a href="footnotes.html#f69"
name="fr69">69</a>]
</p>

<p>
Applications may also use a single subdirectory under
<code>/usr/lib/<var>triplet</var></code>.
</p>

<p>
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.
</p>
</li>
</ol>
<ol type="1" start="4" >
<li>
<p>
The requirement that <code>/usr/local/share/man</code> be
&quot;synonymous&quot; with <code>/usr/local/man</code> is relaxed to a
recommendation
</p>
</li>
</ol>
<ol type="1" start="5" >
<li>
<p>
The requirement that windowmanagers with a single configuration file call it
<code>system.*wmrc</code> is removed, as is the restriction that the window
manager subdirectory be named identically to the window manager name itself.
</p>
</li>
</ol>
<ol type="1" start="6" >
<li>
<p>
The requirement that boot manager configuration files live in
<code>/etc</code>, or at least are symlinked there, is relaxed to a
recommendation.
</p>
</li>
</ol>
<ol type="1" start="7" >
<li>
<p>
The additional directory <code>/run</code> in the root file system is allowed.
<code>/run</code> replaces <code>/var/run</code>, and the subdirectory
<code>/run/lock</code> replaces <code>/var/lock</code>, with the
<code>/var</code> directories replaced by symlinks for backwards compatibility.
<code>/run</code> and <code>/run/lock</code> must follow all of the
requirements in the FHS for <code>/var/run</code> and <code>/var/lock</code>,
respectively, such as file naming conventions, file format requirements, or the
requirement that files be cleared during the boot process.  Files and
directories residing in <code>/run</code> should be stored on a temporary file
system.
</p>
</li>
</ol>
<ol type="1" start="8" >
<li>
<p>
The following directories in the root filesystem are additionally allowed:
<code>/sys</code> and <code>/selinux</code>.  [<a href="footnotes.html#f70"
name="fr70">70</a>]
</p>
</li>
</ol>
<ol type="1" start="9" >
<li>
<p>
On GNU/Hurd systems, the following additional directories are allowed in the
root filesystem: <code>/hurd</code> and <code>/servers</code>.[<a
href="footnotes.html#f71" name="fr71">71</a>]
</p>
</li>
</ol>

<p>
The version of this document referred here can be found in the
<samp>debian-policy</samp> package or on <code><a
href="http://www.debian.org/doc/packaging-manuals/fhs/">FHS (Debian
copy)</a></code> alongside this manual (or, if you have the
<code>debian-policy</code> installed, you can try <code><a
href="file:///usr/share/doc/debian-policy/fhs/">FHS (local copy)</a></code>).
The latest version, which may be a more recent version, may be found on
<code><a href="http://www.pathname.com/fhs/">FHS (upstream)</a></code>.
Specific questions about following the standard may be asked on the
<samp>debian-devel</samp> mailing list, or referred to the FHS mailing list
(see the <code><a href="http://www.pathname.com/fhs/">FHS web site</a></code>
for more information).
</p>

<hr>

<h3><a name="s9.1.2"></a>9.1.2 Site-specific programs</h3>

<p>
As mandated by the FHS, packages must not place any files in
<code>/usr/local</code>, either by putting them in the file system archive to
be unpacked by <code>dpkg</code> or by manipulating them in their maintainer
scripts.
</p>

<p>
However, the package may create empty directories below <code>/usr/local</code>
so that the system administrator knows where to place site-specific files.
These are not directories <em>in</em> <code>/usr/local</code>, but are children
of directories in <code>/usr/local</code>.  These directories
(<code>/usr/local/*/dir/</code>) should be removed on package removal if they
are empty.
</p>

<p>
Note that this applies only to directories <em>below</em>
<code>/usr/local</code>, not <em>in</em> <code>/usr/local</code>.  Packages
must not create sub-directories in the directory <code>/usr/local</code>
itself, except those listed in FHS, section 4.5.  However, you may create
directories below them as you wish.  You must not remove any of the directories
listed in 4.5, even if you created them.
</p>

<p>
Since <code>/usr/local</code> can be mounted read-only from a remote server,
these directories must be created and removed by the <code>postinst</code> and
<code>prerm</code> maintainer scripts and not be included in the
<code>.deb</code> archive.  These scripts must not fail if either of these
operations fail.
</p>

<p>
For example, the <samp>emacsen-common</samp> package could contain something
like
</p>
<pre>
     if [ ! -e /usr/local/share/emacs ]; then
       if mkdir /usr/local/share/emacs 2&gt;/dev/null; then
         if chown root:staff /usr/local/share/emacs; then
           chmod 2775 /usr/local/share/emacs || true
         fi
       fi
     fi
</pre>

<p>
in its <code>postinst</code> script, and
</p>
<pre>
     rmdir /usr/local/share/emacs/site-lisp 2&gt;/dev/null || true
     rmdir /usr/local/share/emacs 2&gt;/dev/null || true
</pre>

<p>
in the <code>prerm</code> script.  (Note that this form is used to ensure that
if the script is interrupted, the directory <code>/usr/local/share/emacs</code>
will still be removed.)
</p>

<p>
If you do create a directory in <code>/usr/local</code> for local additions to
a package, you should ensure that settings in <code>/usr/local</code> take
precedence over the equivalents in <code>/usr</code>.
</p>

<p>
However, because <code>/usr/local</code> and its contents are for exclusive use
of the local administrator, a package must not rely on the presence or absence
of files or directories in <code>/usr/local</code> for normal operation.
</p>

<p>
The <code>/usr/local</code> directory itself and all the subdirectories created
by the package should (by default) have permissions 2775 (group-writable and
set-group-id) and be owned by <samp>root:staff</samp>.
</p>

<hr>

<h3><a name="s9.1.3"></a>9.1.3 The system-wide mail directory</h3>

<p>
The system-wide mail directory is <code>/var/mail</code>.  This directory is
part of the base system and should not be owned by any particular mail agents.
The use of the old location <code>/var/spool/mail</code> is deprecated, even
though the spool may still be physically located there.
</p>

<hr>

<h3><a name="s-fhs-run"></a>9.1.4 <code>/run</code> and <code>/run/lock</code></h3>

<p>
The directory <code>/run</code> is cleared at boot, normally by being a mount
point for a temporary file system.  Packages therefore must not assume that any
files or directories under <code>/run</code> other than <code>/run/lock</code>
exist unless the package has arranged to create those files or directories
since the last reboot.  Normally, this is done by the package via an init
script.  See <a href="#s-writing-init">Writing the scripts, Section 9.3.2</a>
for more information.
</p>

<p>
Packages must not include files or directories under <code>/run</code>, or
under the older <code>/var/run</code> and <code>/var/lock</code> paths.  The
latter paths will normally be symlinks or other redirections to
<code>/run</code> for backwards compatibility.
</p>

<hr>

<h2><a name="s9.2"></a>9.2 Users and groups</h2>

<hr>

<h3><a name="s9.2.1"></a>9.2.1 Introduction</h3>

<p>
The Debian system can be configured to use either plain or shadow passwords.
</p>

<p>
Some user ids (UIDs) and group ids (GIDs) are reserved globally for use by
certain packages.  Because some packages need to include files which are owned
by these users or groups, or need the ids compiled into binaries, these ids
must be used on any Debian system only for the purpose for which they are
allocated.  This is a serious restriction, and we should avoid getting in the
way of local administration policies.  In particular, many sites allocate users
and/or local system groups starting at 100.
</p>

<p>
Apart from this we should have dynamically allocated ids, which should by
default be arranged in some sensible order, but the behavior should be
configurable.
</p>

<p>
Packages other than <samp>base-passwd</samp> must not modify
<code>/etc/passwd</code>, <code>/etc/shadow</code>, <code>/etc/group</code> or
<code>/etc/gshadow</code>.
</p>

<hr>

<h3><a name="s9.2.2"></a>9.2.2 UID and GID classes</h3>

<p>
The UID and GID numbers are divided into classes as follows:
</p>
<dl>
<dt>0-99:</dt>
<dd>
<p>
Globally allocated by the Debian project, the same on every Debian system.
These ids will appear in the <code>passwd</code> and <code>group</code> files
of all Debian systems, new ids in this range being added automatically as the
<samp>base-passwd</samp> package is updated.
</p>

<p>
Packages which need a single statically allocated uid or gid should use one of
these; their maintainers should ask the <samp>base-passwd</samp> maintainer for
ids.
</p>
</dd>
</dl>
<dl>
<dt>100-999:</dt>
<dd>
<p>
Dynamically allocated system users and groups.  Packages which need a user or
group, but can have this user or group allocated dynamically and differently on
each system, should use <samp>adduser --system</samp> to create the group
and/or user.  <code>adduser</code> will check for the existence of the user or
group, and if necessary choose an unused id based on the ranges specified in
<code>adduser.conf</code>.
</p>
</dd>
</dl>
<dl>
<dt>1000-59999:</dt>
<dd>
<p>
Dynamically allocated user accounts.  By default <code>adduser</code> will
choose UIDs and GIDs for user accounts in this range, though
<code>adduser.conf</code> may be used to modify this behavior.
</p>
</dd>
</dl>
<dl>
<dt>60000-64999:</dt>
<dd>
<p>
Globally allocated by the Debian project, but only created on demand.  The ids
are allocated centrally and statically, but the actual accounts are only
created on users' systems on demand.
</p>

<p>
These ids are for packages which are obscure or which require many
statically-allocated ids.  These packages should check for and create the
accounts in <code>/etc/passwd</code> or <code>/etc/group</code> (using
<code>adduser</code> if it has this facility) if necessary.  Packages which are
likely to require further allocations should have a &quot;hole&quot; left after
them in the allocation, to give them room to grow.
</p>
</dd>
</dl>
<dl>
<dt>65000-65533:</dt>
<dd>
<p>
Reserved.
</p>
</dd>
</dl>
<dl>
<dt>65534:</dt>
<dd>
<p>
User <samp>nobody</samp>.  The corresponding gid refers to the group
<samp>nogroup</samp>.
</p>
</dd>
</dl>
<dl>
<dt>65535:</dt>
<dd>
<p>
<samp>(uid_t)(-1) == (gid_t)(-1)</samp> <em>must not</em> be used, because it
is the error return sentinel value.
</p>
</dd>
</dl>

<hr>

<h2><a name="s-sysvinit"></a>9.3 System run levels and <code>init.d</code> scripts</h2>

<hr>

<h3><a name="s-/etc/init.d"></a>9.3.1 Introduction</h3>

<p>
The <code>/etc/init.d</code> directory contains the scripts executed by
<code>init</code> at boot time and when the init state (or
&quot;runlevel&quot;) is changed (see <code>init(8)</code>).
</p>

<p>
There are at least two different, yet functionally equivalent, ways of handling
these scripts.  For the sake of simplicity, this document describes only the
symbolic link method.  However, it must not be assumed by maintainer scripts
that this method is being used, and any automated manipulation of the various
runlevel behaviors by maintainer scripts must be performed using
<code>update-rc.d</code> as described below and not by manually installing or
removing symlinks.  For information on the implementation details of the other
method, implemented in the <samp>file-rc</samp> package, please refer to the
documentation of that package.
</p>

<p>
These scripts are referenced by symbolic links in the
<code>/etc/rc<var>n</var>.d</code> directories.  When changing runlevels,
<code>init</code> looks in the directory <code>/etc/rc<var>n</var>.d</code> for
the scripts it should execute, where <samp><var>n</var></samp> is the runlevel
that is being changed to, or <samp>S</samp> for the boot-up scripts.
</p>

<p>
The names of the links all have the form
<code>S<var>mm</var><var>script</var></code> or
<code>K<var>mm</var><var>script</var></code> where <var>mm</var> is a two-digit
number and <var>script</var> is the name of the script (this should be the same
as the name of the actual script in <code>/etc/init.d</code>).
</p>

<p>
When <code>init</code> changes runlevel first the targets of the links whose
names start with a <samp>K</samp> are executed, each with the single argument
<samp>stop</samp>, followed by the scripts prefixed with an <samp>S</samp>,
each with the single argument <samp>start</samp>.  (The links are those in the
<code>/etc/rc<var>n</var>.d</code> directory corresponding to the new
runlevel.) The <samp>K</samp> links are responsible for killing services and
the <samp>S</samp> link for starting services upon entering the runlevel.
</p>

<p>
For example, if we are changing from runlevel 2 to runlevel 3, init will first
execute all of the <samp>K</samp> prefixed scripts it finds in
<code>/etc/rc3.d</code>, and then all of the <samp>S</samp> prefixed scripts in
that directory.  The links starting with <samp>K</samp> will cause the
referred-to file to be executed with an argument of <samp>stop</samp>, and the
<samp>S</samp> links with an argument of <samp>start</samp>.
</p>

<p>
The two-digit number <var>mm</var> is used to determine the order in which to
run the scripts: low-numbered links have their scripts run first.  For example,
the <samp>K20</samp> scripts will be executed before the <samp>K30</samp>
scripts.  This is used when a certain service must be started before another.
For example, the name server <code>bind</code> might need to be started before
the news server <code>inn</code> so that <code>inn</code> can set up its access
lists.  In this case, the script that starts <code>bind</code> would have a
lower number than the script that starts <code>inn</code> so that it runs
first:
</p>
<pre>
     /etc/rc2.d/S17bind
     /etc/rc2.d/S70inn
</pre>

<p>
The two runlevels 0 (halt) and 6 (reboot) are slightly different.  In these
runlevels, the links with an <samp>S</samp> prefix are still called after those
with a <samp>K</samp> prefix, but they too are called with the single argument
<samp>stop</samp>.
</p>

<hr>

<h3><a name="s-writing-init"></a>9.3.2 Writing the scripts</h3>

<p>
Packages that include daemons for system services should place scripts in
<code>/etc/init.d</code> to start or stop services at boot time or during a
change of runlevel.  These scripts should be named
<code>/etc/init.d/<var>package</var></code>, and they should accept one
argument, saying what to do:
</p>
<dl>
<dt><samp>start</samp></dt>
<dd>
<p>
start the service,
</p>
</dd>
</dl>
<dl>
<dt><samp>stop</samp></dt>
<dd>
<p>
stop the service,
</p>
</dd>
</dl>
<dl>
<dt><samp>restart</samp></dt>
<dd>
<p>
stop and restart the service if it's already running, otherwise start the
service
</p>
</dd>
</dl>
<dl>
<dt><samp>reload</samp></dt>
<dd>
<p>
cause the configuration of the service to be reloaded without actually stopping
and restarting the service,
</p>
</dd>
</dl>
<dl>
<dt><samp>force-reload</samp></dt>
<dd>
<p>
cause the configuration to be reloaded if the service supports this, otherwise
restart the service.
</p>
</dd>
</dl>

<p>
The <samp>start</samp>, <samp>stop</samp>, <samp>restart</samp>, and
<samp>force-reload</samp> options should be supported by all scripts in
<code>/etc/init.d</code>, the <samp>reload</samp> option is optional.
</p>

<p>
The <code>init.d</code> scripts must ensure that they will behave sensibly
(i.e., returning success and not starting multiple copies of a service) if
invoked with <samp>start</samp> when the service is already running, or with
<samp>stop</samp> when it isn't, and that they don't kill unfortunately-named
user processes.  The best way to achieve this is usually to use
<code>start-stop-daemon</code> with the <samp>--oknodo</samp> option.
</p>

<p>
Be careful of using <samp>set -e</samp> in <code>init.d</code> scripts.
Writing correct <code>init.d</code> scripts requires accepting various error
exit statuses when daemons are already running or already stopped without
aborting the <code>init.d</code> script, and common <code>init.d</code>
function libraries are not safe to call with <samp>set -e</samp> in effect[<a
href="footnotes.html#f72" name="fr72">72</a>].  For <samp>init.d</samp>
scripts, it's often easier to not use <samp>set -e</samp> and instead check the
result of each command separately.
</p>

<p>
If a service reloads its configuration automatically (as in the case of
<code>cron</code>, for example), the <samp>reload</samp> option of the
<code>init.d</code> script should behave as if the configuration has been
reloaded successfully.
</p>

<p>
The <code>/etc/init.d</code> scripts must be treated as configuration files,
either (if they are present in the package, that is, in the .deb file) by
marking them as <samp>conffile</samp>s, or, (if they do not exist in the .deb)
by managing them correctly in the maintainer scripts (see <a
href="ch-files.html#s-config-files">Configuration files, Section 10.7</a>).
This is important since we want to give the local system administrator the
chance to adapt the scripts to the local system, e.g., to disable a service
without de-installing the package, or to specify some special command line
options when starting a service, while making sure their changes aren't lost
during the next package upgrade.
</p>

<p>
These scripts should not fail obscurely when the configuration files remain but
the package has been removed, as configuration files remain on the system after
the package has been removed.  Only when <code>dpkg</code> is executed with the
<samp>--purge</samp> option will configuration files be removed.  In
particular, as the <code>/etc/init.d/<var>package</var></code> script itself is
usually a <samp>conffile</samp>, it will remain on the system if the package is
removed but not purged.  Therefore, you should include a <samp>test</samp>
statement at the top of the script, like this:
</p>
<pre>
     test -f <var>program-executed-later-in-script</var> || exit 0
</pre>

<p>
Often there are some variables in the <code>init.d</code> scripts whose values
control the behavior of the scripts, and which a system administrator is likely
to want to change.  As the scripts themselves are frequently
<samp>conffile</samp>s, modifying them requires that the administrator merge in
their changes each time the package is upgraded and the <samp>conffile</samp>
changes.  To ease the burden on the system administrator, such configurable
values should not be placed directly in the script.  Instead, they should be
placed in a file in <code>/etc/default</code>, which typically will have the
same base name as the <code>init.d</code> script.  This extra file should be
sourced by the script when the script runs.  It must contain only variable
settings and comments in SUSv3 <code>sh</code> format.  It may either be a
<samp>conffile</samp> or a configuration file maintained by the package
maintainer scripts.  See <a href="ch-files.html#s-config-files">Configuration
files, Section 10.7</a> for more details.
</p>

<p>
To ensure that vital configurable values are always available, the
<code>init.d</code> script should set default values for each of the shell
variables it uses, either before sourcing the <code>/etc/default/</code> file
or afterwards using something like the <samp>: ${VAR:=default}</samp> syntax.
Also, the <code>init.d</code> script must behave sensibly and not fail if the
<code>/etc/default</code> file is deleted.
</p>

<p>
Files and directories under <code>/run</code>, including ones referred to via
the compatibility paths <code>/var/run</code> and <code>/var/lock</code>, are
normally stored on a temporary filesystem and are normally not persistent
across a reboot.  The <code>init.d</code> scripts must handle this correctly.
This will typically mean creating any required subdirectories dynamically when
the <code>init.d</code> script is run.  See <a
href="#s-fhs-run"><code>/run</code> and <code>/run/lock</code>, Section
9.1.4</a> for more information.
</p>

<hr>

<h3><a name="s9.3.3"></a>9.3.3 Interfacing with the initscript system</h3>

<p>
Maintainers should use the abstraction layer provided by the
<code>update-rc.d</code> and <code>invoke-rc.d</code> programs to deal with
initscripts in their packages' scripts such as <code>postinst</code>,
<code>prerm</code> and <code>postrm</code>.
</p>

<p>
Directly managing the /etc/rc?.d links and directly invoking the
<code>/etc/init.d/</code> initscripts should be done only by packages providing
the initscript subsystem (such as <code>sysv-rc</code> and
<code>file-rc</code>).
</p>

<hr>

<h4><a name="s9.3.3.1"></a>9.3.3.1 Managing the links</h4>

<p>
The program <code>update-rc.d</code> is provided for package maintainers to
arrange for the proper creation and removal of
<code>/etc/rc<var>n</var>.d</code> symbolic links, or their functional
equivalent if another method is being used.  This may be used by maintainers in
their packages' <code>postinst</code> and <code>postrm</code> scripts.
</p>

<p>
You must not include any <code>/etc/rc<var>n</var>.d</code> symbolic links in
the actual archive or manually create or remove the symbolic links in
maintainer scripts; you must use the <code>update-rc.d</code> program instead.
(The former will fail if an alternative method of maintaining runlevel
information is being used.) You must not include the
<code>/etc/rc<var>n</var>.d</code> directories themselves in the archive
either.  (Only the <samp>sysvinit</samp> package may do so.)
</p>

<p>
By default <code>update-rc.d</code> will start services in each of the
multi-user state runlevels (2, 3, 4, and 5) and stop them in the halt runlevel
(0), the single-user runlevel (1) and the reboot runlevel (6).  The system
administrator will have the opportunity to customize runlevels by simply
adding, moving, or removing the symbolic links in
<code>/etc/rc<var>n</var>.d</code> if symbolic links are being used, or by
modifying <code>/etc/runlevel.conf</code> if the <samp>file-rc</samp> method is
being used.
</p>

<p>
To get the default behavior for your package, put in your <code>postinst</code>
script
</p>
<pre>
     		update-rc.d <var>package</var> defaults
</pre>

<p>
and in your <code>postrm</code>
</p>
<pre>
     		if [ &quot;$1&quot; = purge ]; then
     		update-rc.d <var>package</var> remove
     		fi
</pre>

<p>
.  Note that if your package changes runlevels or priority, you may have to
remove and recreate the links, since otherwise the old links may persist.
Refer to the documentation of <code>update-rc.d</code>.
</p>

<p>
This will use a default sequence number of 20.  If it does not matter when or
in which order the <code>init.d</code> script is run, use this default.  If it
does, then you should talk to the maintainer of the <code>sysvinit</code>
package or post to <samp>debian-devel</samp>, and they will help you choose a
number.
</p>

<p>
For more information about using <samp>update-rc.d</samp>, please consult its
man page <code>update-rc.d(8)</code>.
</p>

<hr>

<h4><a name="s9.3.3.2"></a>9.3.3.2 Running initscripts</h4>

<p>
The program <code>invoke-rc.d</code> is provided to make it easier for package
maintainers to properly invoke an initscript, obeying runlevel and other
locally-defined constraints that might limit a package's right to start, stop
and otherwise manage services.  This program may be used by maintainers in
their packages' scripts.
</p>

<p>
The package maintainer scripts must use <code>invoke-rc.d</code> to invoke the
<code>/etc/init.d/*</code> initscripts, instead of calling them directly.
</p>

<p>
By default, <code>invoke-rc.d</code> will pass any action requests (start,
stop, reload, restart...) to the <code>/etc/init.d</code> script, filtering out
requests to start or restart a service out of its intended runlevels.
</p>

<p>
Most packages will simply need to change:
</p>
<pre>
     /etc/init.d/&lt;package&gt;
     	      &lt;action&gt;
</pre>

<p>
in their <code>postinst</code> and <code>prerm</code> scripts to:
</p>
<pre>
     	if which invoke-rc.d &gt;/dev/null 2&gt;&amp;1; then
     		invoke-rc.d <var>package</var> &lt;action&gt;
     	else
     		/etc/init.d/<var>package</var> &lt;action&gt;
     	fi
</pre>

<p>
A package should register its initscript services using
<code>update-rc.d</code> before it tries to invoke them using
<code>invoke-rc.d</code>.  Invocation of unregistered services may fail.
</p>

<p>
For more information about using <code>invoke-rc.d</code>, please consult its
man page <code>invoke-rc.d(8)</code>.
</p>

<hr>

<h3><a name="s9.3.4"></a>9.3.4 Boot-time initialization</h3>

<p>
There used to be another directory, <code>/etc/rc.boot</code>, which contained
scripts which were run once per machine boot.  This has been deprecated in
favour of links from <code>/etc/rcS.d</code> to files in
<code>/etc/init.d</code> as described in <a href="#s-/etc/init.d">Introduction,
Section 9.3.1</a>.  Packages must not place files in <code>/etc/rc.boot</code>.
</p>

<hr>

<h3><a name="s9.3.5"></a>9.3.5 Example</h3>

<p>
An example on which you can base your <code>/etc/init.d</code> scripts is found
in <code>/etc/init.d/skeleton</code>.
</p>

<hr>

<h2><a name="s9.4"></a>9.4 Console messages from <code>init.d</code> scripts</h2>

<p>
This section describes the formats to be used for messages written to standard
output by the <code>/etc/init.d</code> scripts.  The intent is to improve the
consistency of Debian's startup and shutdown look and feel.  For this reason,
please look very carefully at the details.  We want the messages to have the
same format in terms of wording, spaces, punctuation and case of letters.
</p>

<p>
Here is a list of overall rules that should be used for messages generated by
<code>/etc/init.d</code> scripts.
</p>
<ul>
<li>
<p>
The message should fit in one line (fewer than 80 characters), start with a
capital letter and end with a period (<samp>.</samp>) and line feed
(<samp>&quot;\n&quot;</samp>).
</p>
</li>
</ul>
<ul>
<li>
<p>
If the script is performing some time consuming task in the background (not
merely starting or stopping a program, for instance), an ellipsis (three dots:
<samp>...</samp>) should be output to the screen, with no leading or tailing
whitespace or line feeds.
</p>
</li>
</ul>
<ul>
<li>
<p>
The messages should appear as if the computer is telling the user what it is
doing (politely :-), but should not mention &quot;it&quot; directly.  For
example, instead of:
</p>
<pre>
     I'm starting network daemons: nfsd mountd.
</pre>

<p>
the message should say
</p>
<pre>
     Starting network daemons: nfsd mountd.
</pre>
</li>
</ul>

<p>
<samp>init.d</samp> script should use the following standard message formats
for the situations enumerated below.
</p>
<ul>
<li>
<p>
When daemons are started
</p>

<p>
If the script starts one or more daemons, the output should look like this (a
single line, no leading spaces):
</p>
<pre>
     Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
</pre>

<p>
The <var>description</var> should describe the subsystem the daemon or set of
daemons are part of, while <var>daemon-1</var> up to <var>daemon-n</var> denote
each daemon's name (typically the file name of the program).
</p>

<p>
For example, the output of <code>/etc/init.d/lpd</code> would look like:
</p>
<pre>
     Starting printer spooler: lpd.
</pre>

<p>
This can be achieved by saying
</p>
<pre>
     echo -n &quot;Starting printer spooler: lpd&quot;
     start-stop-daemon --start --quiet --exec /usr/sbin/lpd
     echo &quot;.&quot;
</pre>

<p>
in the script.  If there are more than one daemon to start, the output should
look like this:
</p>
<pre>
     echo -n &quot;Starting remote file system services:&quot;
     echo -n &quot; nfsd&quot;; start-stop-daemon --start --quiet nfsd
     echo -n &quot; mountd&quot;; start-stop-daemon --start --quiet mountd
     echo -n &quot; ugidd&quot;; start-stop-daemon --start --quiet ugidd
     echo &quot;.&quot;
</pre>

<p>
This makes it possible for the user to see what is happening and when the final
daemon has been started.  Care should be taken in the placement of white
spaces: in the example above the system administrators can easily comment out a
line if they don't want to start a specific daemon, while the displayed message
still looks good.
</p>
</li>
</ul>
<ul>
<li>
<p>
When a system parameter is being set
</p>

<p>
If you have to set up different system parameters during the system boot, you
should use this format:
</p>
<pre>
     Setting <var>parameter</var> to &quot;<var>value</var>&quot;.
</pre>

<p>
You can use a statement such as the following to get the quotes right:
</p>
<pre>
     echo &quot;Setting DNS domainname to \&quot;$domainname\&quot;.&quot;
</pre>

<p>
Note that the same symbol (<samp>&quot;</samp>) is used for the left and right
quotation marks.  A grave accent (<samp>`</samp>) is not a quote character;
neither is an apostrophe (<samp>'</samp>).
</p>
</li>
</ul>
<ul>
<li>
<p>
When a daemon is stopped or restarted
</p>

<p>
When you stop or restart a daemon, you should issue a message identical to the
startup message, except that <samp>Starting</samp> is replaced with
<samp>Stopping</samp> or <samp>Restarting</samp> respectively.
</p>

<p>
For example, stopping the printer daemon will look like this:
</p>
<pre>
     Stopping printer spooler: lpd.
</pre>
</li>
</ul>
<ul>
<li>
<p>
When something is executed
</p>

<p>
There are several examples where you have to run a program at system startup or
shutdown to perform a specific task, for example, setting the system's clock
using <code>netdate</code> or killing all processes when the system shuts down.
Your message should look like this:
</p>
<pre>
     Doing something very useful...done.
</pre>

<p>
You should print the <samp>done.</samp> immediately after the job has been
completed, so that the user is informed why they have to wait.  You can get
this behavior by saying
</p>
<pre>
     echo -n &quot;Doing something very useful...&quot;
     do_something
     echo &quot;done.&quot;
</pre>

<p>
in your script.
</p>
</li>
</ul>
<ul>
<li>
<p>
When the configuration is reloaded
</p>

<p>
When a daemon is forced to reload its configuration files you should use the
following format:
</p>
<pre>
     Reloading <var>description</var> configuration...done.
</pre>

<p>
where <var>description</var> is the same as in the daemon starting message.
</p>
</li>
</ul>

<hr>

<h2><a name="s-cron-jobs"></a>9.5 Cron jobs</h2>

<p>
Packages must not modify the configuration file <code>/etc/crontab</code>, and
they must not modify the files in <code>/var/spool/cron/crontabs</code>.
</p>

<p>
If a package wants to install a job that has to be executed via cron, it should
place a file named as specified in <a href="#s-cron-files">Cron job file names,
Section 9.5.1</a> into one or more of the following directories:
</p>
<pre>
     /etc/cron.hourly
     /etc/cron.daily
     /etc/cron.weekly
     /etc/cron.monthly
</pre>

<p>
As these directory names imply, the files within them are executed on an
hourly, daily, weekly, or monthly basis, respectively.  The exact times are
listed in <code>/etc/crontab</code>.
</p>

<p>
All files installed in any of these directories must be scripts (e.g., shell
scripts or Perl scripts) so that they can easily be modified by the local
system administrator.  In addition, they must be treated as configuration
files.
</p>

<p>
If a certain job has to be executed at some other frequency or at a specific
time, the package should install a file in <code>/etc/cron.d</code> with a name
as specified in <a href="#s-cron-files">Cron job file names, Section 9.5.1</a>.
This file uses the same syntax as <code>/etc/crontab</code> and is processed by
<code>cron</code> automatically.  The file must also be treated as a
configuration file.  (Note that entries in the <code>/etc/cron.d</code>
directory are not handled by <code>anacron</code>.  Thus, you should only use
this directory for jobs which may be skipped if the system is not running.)
</p>

<p>
Unlike <code>crontab</code> files described in the IEEE Std 1003.1-2008
(POSIX.1) available from <code><a
href="http://www.opengroup.org/onlinepubs/9699919799/">The Open
Group</a></code>, the files in <code>/etc/cron.d</code> and the file
<code>/etc/crontab</code> have seven fields; namely:
</p>
<ol type="1" start="1" >
<li>
<p>
Minute [0,59]
</p>
</li>
</ol>
<ol type="1" start="2" >
<li>
<p>
Hour [0,23]
</p>
</li>
</ol>
<ol type="1" start="3" >
<li>
<p>
Day of the month [1,31]
</p>
</li>
</ol>
<ol type="1" start="4" >
<li>
<p>
Month of the year [1,12]
</p>
</li>
</ol>
<ol type="1" start="5" >
<li>
<p>
Day of the week ([0,6] with 0=Sunday)
</p>
</li>
</ol>
<ol type="1" start="6" >
<li>
<p>
Username
</p>
</li>
</ol>
<ol type="1" start="7" >
<li>
<p>
Command to be run
</p>
</li>
</ol>

<p>
Ranges of numbers are allowed.  Ranges are two numbers separated with a hyphen.
The specified range is inclusive.  Lists are allowed.  A list is a set of
numbers (or ranges) separated by commas.  Step values can be used in
conjunction with ranges.
</p>

<p>
The scripts or <samp>crontab</samp> entries in these directories should check
if all necessary programs are installed before they try to execute them.
Otherwise, problems will arise when a package was removed but not purged since
configuration files are kept on the system in this situation.
</p>

<p>
Any <samp>cron</samp> daemon must provide <code>/usr/bin/crontab</code> and
support normal <samp>crontab</samp> entries as specified in POSIX.  The daemon
must also support names for days and months, ranges, and step values.  It has
to support <code>/etc/crontab</code>, and correctly execute the scripts in
<code>/etc/cron.d</code>.  The daemon must also correctly execute scripts in
<code>/etc/cron.{hourly,daily,weekly,monthly}</code>.
</p>

<hr>

<h3><a name="s-cron-files"></a>9.5.1 Cron job file names</h3>

<p>
The file name of a cron job file should normally match the name of the package
from which it comes.
</p>

<p>
If a package supplies multiple cron job files files in the same directory, the
file names should all start with the name of the package (possibly modified as
described below) followed by a hyphen (<samp>-</samp>) and a suitable suffix.
</p>

<p>
A cron job file name must not include any period or plus characters
(<samp>.</samp> or <samp>+</samp>) characters as this will cause cron to ignore
the file.  Underscores (<samp>_</samp>) should be used instead of
<samp>.</samp> and <samp>+</samp> characters.
</p>

<hr>

<h2><a name="s-menus"></a>9.6 Menus</h2>

<p>
The Debian <samp>menu</samp> package provides a standard interface between
packages providing applications and <em>menu programs</em> (either X window
managers or text-based menu programs such as <code>pdmenu</code>).
</p>

<p>
All packages that provide applications that need not be passed any special
command line arguments for normal operation should register a menu entry for
those applications, so that users of the <samp>menu</samp> package will
automatically get menu entries in their window managers, as well in shells like
<samp>pdmenu</samp>.
</p>

<p>
Menu entries should follow the current menu policy.
</p>

<p>
The menu policy can be found in the <samp>menu-policy</samp> files in the
<samp>debian-policy</samp> package.  It is also available from the Debian web
mirrors at <samp><code><a
href="http://www.debian.org/doc/packaging-manuals/menu-policy/">/doc/packaging-manuals/menu-policy/</a></code></samp>.
</p>

<p>
Please also refer to the <em>Debian Menu System</em> documentation that comes
with the <code>menu</code> package for information about how to register your
applications.
</p>

<hr>

<h2><a name="s-mime"></a>9.7 Multimedia handlers</h2>

<p>
MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049) is a mechanism for
encoding files and data streams and providing meta-information about them, in
particular their type (e.g.  audio or video) and format (e.g.  PNG, HTML, MP3).
</p>

<p>
Registration of MIME type handlers allows programs like mail user agents and
web browsers to invoke these handlers to view, edit or display MIME types they
don't support directly.
</p>

<p>
Packages which provide the ability to view/show/play, compose, edit or print
MIME types should register themselves as such following the current MIME
support policy.
</p>

<p>
The <code>mime-support</code> package provides the <code>update-mime</code>
program which allows packages to register programs that can show, compose, edit
or print MIME types.
</p>

<p>
Packages containing such programs must register them with
<code>update-mime</code> as documented in <code>update-mime(8)</code>.  They
should <em>not</em> depend on, recommend, or suggest <code>mime-support</code>.
Instead, they should just put something like the following in the
<samp>postinst</samp> and <samp>postrm</samp> scripts:
</p>

<pre>
       if [ -x /usr/sbin/update-mime ]; then
           update-mime
       fi
</pre>

<hr>

<h2><a name="s9.8"></a>9.8 Keyboard configuration</h2>

<p>
To achieve a consistent keyboard configuration so that all applications
interpret a keyboard event the same way, all programs in the Debian
distribution must be configured to comply with the following guidelines.
</p>

<p>
The following keys must have the specified interpretations:
</p>
<dl>
<dt><samp>&lt;--</samp></dt>
<dd>
<p>
delete the character to the left of the cursor
</p>
</dd>
</dl>
<dl>
<dt><samp>Delete</samp></dt>
<dd>
<p>
delete the character to the right of the cursor
</p>
</dd>
</dl>
<dl>
<dt><samp>Control+H</samp></dt>
<dd>
<p>
emacs: the help prefix
</p>
</dd>
</dl>

<p>
The interpretation of any keyboard events should be independent of the terminal
that is used, be it a virtual console, an X terminal emulator, an rlogin/telnet
session, etc.
</p>

<p>
The following list explains how the different programs should be set up to
achieve this:
</p>
<ul>
<li>
<p>
<samp>&lt;--</samp> generates <samp>KB_BackSpace</samp> in X.
</p>
</li>
</ul>
<ul>
<li>
<p>
<samp>Delete</samp> generates <samp>KB_Delete</samp> in X.
</p>
</li>
</ul>
<ul>
<li>
<p>
X translations are set up to make <samp>KB_Backspace</samp> generate ASCII DEL,
and to make <samp>KB_Delete</samp> generate <samp>ESC [ 3 ~</samp> (this is the
vt220 escape code for the &quot;delete character&quot; key).  This must be done
by loading the X resources using <code>xrdb</code> on all local X displays, not
using the application defaults, so that the translation resources used
correspond to the <code>xmodmap</code> settings.
</p>
</li>
</ul>
<ul>
<li>
<p>
The Linux console is configured to make <samp>&lt;--</samp> generate DEL, and
<samp>Delete</samp> generate <samp>ESC [ 3 ~</samp>.
</p>
</li>
</ul>
<ul>
<li>
<p>
X applications are configured so that <samp>&lt;</samp> deletes left, and
<samp>Delete</samp> deletes right.  Motif applications already work like this.
</p>
</li>
</ul>
<ul>
<li>
<p>
Terminals should have <samp>stty erase ^?</samp> .
</p>
</li>
</ul>
<ul>
<li>
<p>
The <samp>xterm</samp> terminfo entry should have <samp>ESC [ 3 ~</samp> for
<samp>kdch1</samp>, just as for <samp>TERM=linux</samp> and
<samp>TERM=vt220</samp>.
</p>
</li>
</ul>
<ul>
<li>
<p>
Emacs is programmed to map <samp>KB_Backspace</samp> or the <samp>stty
erase</samp> character to <samp>delete-backward-char</samp>, and
<samp>KB_Delete</samp> or <samp>kdch1</samp> to
<samp>delete-forward-char</samp>, and <samp>^H</samp> to <samp>help</samp> as
always.
</p>
</li>
</ul>
<ul>
<li>
<p>
Other applications use the <samp>stty erase</samp> character and
<samp>kdch1</samp> for the two delete keys, with ASCII DEL being &quot;delete
previous character&quot; and <samp>kdch1</samp> being &quot;delete character
under cursor&quot;.
</p>
</li>
</ul>

<p>
This will solve the problem except for the following cases:
</p>
<ul>
<li>
<p>
Some terminals have a <samp>&lt;--</samp> key that cannot be made to produce
anything except <samp>^H</samp>.  On these terminals Emacs help will be
unavailable on <samp>^H</samp> (assuming that the <samp>stty erase</samp>
character takes precedence in Emacs, and has been set correctly).  <samp>M-x
help</samp> or <samp>F1</samp> (if available) can be used instead.
</p>
</li>
</ul>
<ul>
<li>
<p>
Some operating systems use <samp>^H</samp> for <samp>stty erase</samp>.
However, modern telnet versions and all rlogin versions propagate
<samp>stty</samp> settings, and almost all UNIX versions honour <samp>stty
erase</samp>.  Where the <samp>stty</samp> settings are not propagated
correctly, things can be made to work by using <samp>stty</samp> manually.
</p>
</li>
</ul>
<ul>
<li>
<p>
Some systems (including previous Debian versions) use <code>xmodmap</code> to
arrange for both <samp>&lt;--</samp> and <samp>Delete</samp> to generate
<samp>KB_Delete</samp>.  We can change the behavior of their X clients using
the same X resources that we use to do it for our own clients, or configure our
clients using their resources when things are the other way around.  On
displays configured like this <samp>Delete</samp> will not work, but
<samp>&lt;--</samp> will.
</p>
</li>
</ul>
<ul>
<li>
<p>
Some operating systems have different <samp>kdch1</samp> settings in their
<samp>terminfo</samp> database for <samp>xterm</samp> and others.  On these
systems the <samp>Delete</samp> key will not work correctly when you log in
from a system conforming to our policy, but <samp>&lt;--</samp> will.
</p>
</li>
</ul>

<hr>

<h2><a name="s9.9"></a>9.9 Environment variables</h2>

<p>
A program must not depend on environment variables to get reasonable defaults.
(That's because these environment variables would have to be set in a
system-wide configuration file like <code>/etc/profile</code>, which is not
supported by all shells.)
</p>

<p>
If a program usually depends on environment variables for its configuration,
the program should be changed to fall back to a reasonable default
configuration if these environment variables are not present.  If this cannot
be done easily (e.g., if the source code of a non-free program is not
available), the program must be replaced by a small &quot;wrapper&quot; shell
script which sets the environment variables if they are not already defined,
and calls the original program.
</p>

<p>
Here is an example of a wrapper script for this purpose:
</p>
<pre>
     #!/bin/sh
     BAR=${BAR:-/var/lib/fubar}
     export BAR
     exec /usr/lib/foo/foo &quot;$@&quot;
</pre>

<p>
Furthermore, as <code>/etc/profile</code> is a configuration file of the
<code>base-files</code> package, other packages must not put any environment
variables or other commands into that file.
</p>

<hr>

<h2><a name="s-doc-base"></a>9.10 Registering Documents using doc-base</h2>

<p>
The <code>doc-base</code> package implements a flexible mechanism for handling
and presenting documentation.  The recommended practice is for every Debian
package that provides online documentation (other than just manual pages) to
register these documents with <code>doc-base</code> by installing a
<code>doc-base</code> control file in <code>/usr/share/doc-base/</code>.
</p>

<p>
Please refer to the documentation that comes with the <code>doc-base</code>
package for information and details.
</p>

<hr>

<p>
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Debian Policy Manual
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version 3.9.3.1, 2012-03-13<br>
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<a href="ch-scope.html#s-authors">The Debian Policy Mailing List</a><br>
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debian-policy 3.9.3.1 / usr / share / doc / debian-policy / policy.html / ch-opersys.html
