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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
]>
<article id="index">
<articleinfo>
<title>Desktop Entry Specification</title>
<releaseinfo>Version 1.1-draft</releaseinfo>
<date>4 Mar 2008</date>
<authorgroup>
<author>
<firstname>Preston</firstname>
<surname>Brown</surname>
<affiliation>
<address>
<email>pbrown@kde.org</email>
</address>
</affiliation>
</author>
<author>
<firstname>Jonathan</firstname>
<surname>Blandford</surname>
<affiliation>
<address>
<email>jrb@redhat.com</email>
</address>
</affiliation>
</author>
<author>
<firstname>Owen</firstname>
<surname>Taylor</surname>
<affiliation>
<address>
<email>otaylor@gtk.org</email>
</address>
</affiliation>
</author>
<author>
<firstname>Vincent</firstname>
<surname>Untz</surname>
<affiliation>
<address>
<email>vuntz@gnome.org</email>
</address>
</affiliation>
</author>
<author>
<firstname>Waldo</firstname>
<surname>Bastian</surname>
<affiliation>
<address>
<email>waldo.bastian@intel.com</email>
</address>
</affiliation>
</author>
</authorgroup>
</articleinfo>
<sect1 id="introduction">
<title>Introduction</title>
<para>
Both the KDE and GNOME desktop environments have adopted a similar
format for "desktop entries", or configuration files describing how a
particular program is to be launched, how it appears in menus, etc.
It is to the larger community's benefit that a unified standard be
agreed upon by all parties such that interoperation between the two
environments, and indeed any additional environments that implement
the specification, becomes simpler.
</para>
</sect1>
<sect1 id="basic-format">
<title>Basic format of the file</title>
<para>
Desktop entry files should have the <filename>.desktop</filename>
extension, except for files of <varname>Type</varname>
<constant>Directory</constant> which should have the
<filename>.directory</filename> extension. Determining file type on basis
of extension makes determining the file type very easy and quick.
When no file extension is present, the desktop system should
fall back to recognition via "magic detection".
</para>
<para>
Desktop entry files are encoded in UTF-8. A file is interpreted as a
series of lines that are separated by linefeed characters. Case is
significant everywhere in the file.
</para>
<para>
Compliant implementations MUST not remove any fields from the file,
even if they don't support them. Such fields must be maintained in a
list somewhere, and if the file is "rewritten", they will be included.
This ensures that any desktop-specific extensions will be preserved
even if another system accesses and changes the file.
</para>
<sect2 id="comments">
<title>Comments</title>
<para>
Lines beginning with a <literal>#</literal> and blank lines are
considered comments and will be ignored, however they should be
preserved across reads and writes of the desktop entry file.
</para>
<para>
Comment lines are uninterpreted and may contain any character
(except for LF). However, using UTF-8 for comment lines that
contain characters not in ASCII is encouraged.
</para>
</sect2>
<sect2 id="group-header">
<title>Group headers</title>
<para>
A group header with name <literal>groupname</literal> is a line in the
format:
</para>
<programlisting>[groupname]</programlisting>
<para>
Group names may contain all ASCII characters except for
<literal>[</literal> and <literal>]</literal> and control characters.
</para>
<para>
Multiple groups may not have the same name.
</para>
<para>
All <literal>{key,value}</literal> pairs following a group header until
a new group header belong to the group.
</para>
<para>
The basic format of the desktop entry file requires that there be
a group header named <literal>Desktop Entry</literal>. There may
be other groups present in the file, but this is the most
important group which explicitly needs to be supported. This
group should also be used as the "magic key" for automatic MIME
type detection. There should be nothing preceding this group in
the desktop entry file but possibly one or more comments.
</para>
</sect2>
<sect2 id="entries">
<title>Entries</title>
<para>
Entries in the file are <literal>{key,value}</literal> pairs in the
format:
</para>
<programlisting>Key=Value</programlisting>
<para>
Space before and after the equals sign should be ignored; the
<literal>=</literal> sign is the actual delimiter.
</para>
<para>
Only the characters <literal>A-Za-z0-9-</literal> may be used in
key names.
</para>
<para>
As the case is significant, the keys <varname>Name</varname> and
<varname>NAME</varname> are not equivalent.
</para>
<para>
Multiple keys in the same group may not have the same name. Keys in
different groups may have the same name.
</para>
</sect2>
</sect1>
<sect1 id="value-types">
<title>Possible value types</title>
<para>
The value types recognized are <literal>string</literal>,
<literal>localestring</literal>,
<literal>boolean</literal>, and
<literal>numeric</literal>.
</para>
<itemizedlist>
<listitem>
<para>
Values of type <literal>string</literal> may contain all ASCII
characters except for control characters.
</para>
</listitem>
<listitem>
<para>
Values of type <literal>localestring</literal> are user displayable,
and are encoded in UTF-8.
</para>
</listitem>
<listitem>
<para>
Values of type <literal>boolean</literal> must either be the string
<literal>true</literal> or <literal>false</literal>.
</para>
</listitem>
<listitem>
<para>
Values of type <literal>numeric</literal> must be a valid floating
point number as recognized by the <literal>%f</literal> specifier for
<function>scanf</function> in the <literal>C</literal> locale.
</para>
</listitem>
</itemizedlist>
<para>
The escape sequences <literal>\s</literal>, <literal>\n</literal>,
<literal>\t</literal>, <literal>\r</literal>, and
<literal>\\</literal> are supported for values of type
<literal>string</literal> and <literal>localestring</literal>, meaning
ASCII space, newline, tab, carriage return, and backslash, respectively.
</para>
<para>
Some keys can have multiple values. In such a case, the value of the key
is specified as a plural: for example, <literal>string(s)</literal>. The
multiple values should be separated by a semicolon, and the value of the
key should have a semicolon as trailing character. Semicolons in these
values need to be escaped using <literal>\;</literal>.
</para>
</sect1>
<sect1 id="localized-keys">
<title>Localized values for keys</title>
<para>
Keys with type <literal>localestring</literal> may be postfixed by
[<replaceable>LOCALE</replaceable>],
where <replaceable>LOCALE</replaceable> is the locale type of the
entry. <replaceable>LOCALE</replaceable> must be of the form
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>.<replaceable>ENCODING</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
where
<literal>_<replaceable>COUNTRY</replaceable></literal>,
<literal>.<replaceable>ENCODING</replaceable></literal>,
and <literal>@<replaceable>MODIFIER</replaceable></literal>
may be omitted. If a postfixed key occurs, the same
key must be also present without the postfix.
</para>
<para>
When reading in the desktop entry file, the value of the key is
selected by matching the current POSIX locale for the
<varname>LC_MESSAGES</varname> category against the
<replaceable>LOCALE</replaceable> postfixes of all occurrences
of the key, with the
<literal>.<replaceable>ENCODING</replaceable></literal> part
stripped.
</para>
<para>
The matching is done as follows. If
<varname>LC_MESSAGES</varname> is of the form
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>.<replaceable>ENCODING</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
then it will match a key of the form
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>@<replaceable>MODIFIER</replaceable></literal>.
If such a key does not exist, it will attempt to match
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>
followed by
<literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal>.
Then, a match against <replaceable>lang</replaceable> by itself
will be attempted. Finally, if no matching key is found the
required key without a locale specified is used. The encoding
from the <varname>LC_MESSAGES</varname> value is ignored
when matching.
</para>
<para>
If <varname>LC_MESSAGES</varname> does not have a <replaceable>MODIFIER</replaceable>
field, then no key with a modifier will be matched. Similarly, if
<varname>LC_MESSAGES</varname> does not have a <replaceable>COUNTRY</replaceable>
field, then no key with a country specified will be matched. If
<varname>LC_MESSAGES</varname> just has a <replaceable>lang</replaceable> field, then
it will do a straight match to a key with a similar value. The
following table lists possible matches of various <varname>LC_MESSAGES</varname> values in
the order in which they are matched. Note that the
<replaceable>ENCODING</replaceable> field isn't shown.
</para>
<table>
<title>Locale Matching</title>
<tgroup cols="2">
<thead>
<row>
<entry><varname>LC_MESSAGES</varname> value</entry>
<entry>Possible keys in order of matching</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>@<replaceable>MODIFIER</replaceable></literal></entry>
<entry>
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>,
<literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
<literal><replaceable>lang</replaceable></literal>,
default value
</entry>
</row>
<row>
<entry><literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal></entry>
<entry>
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>,
<replaceable>lang</replaceable>,
default value
</entry>
</row>
<row>
<entry><literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal></entry>
<entry>
<literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
<replaceable>lang</replaceable>,
default value
</entry>
</row>
<row>
<entry><replaceable>lang</replaceable></entry>
<entry>
<replaceable>lang</replaceable>,
default value
</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
For example, if the current value of the <varname>LC_MESSAGES</varname> category
is <literal>sr_YU@Latn</literal> and the desktop file includes:
</para>
<programlisting>
Name=Foo
Name[sr_YU]=...
Name[sr@Latn]=...
Name[sr]=...</programlisting>
<para>
then the value of the <varname>Name</varname> keyed by <literal>sr_YU</literal> is used.
</para>
</sect1>
<sect1 id="recognized-keys">
<title>Recognized desktop entry keys</title>
<para>
Keys are either OPTIONAL or REQUIRED. If a key is OPTIONAL it may or
may not be present in the file. However, if it isn't, the
implementation of the standard should not blow up, it must provide
some sane defaults.
</para>
<para>
Some keys only make sense in the context when another particular key
is also present and set to a specific value. Those keys should not be
used if the particular key is not present or not set to the specific
value. For example, the <varname>Terminal</varname> key can only be used
when the value of the <varname>Type</varname> key is
<constant>Application</constant>.
</para>
<para>
If a REQUIRED key is only valid in the context of another key set to a
specific value, then it has to be present only if the other key is set to
the specific value. For example, the <varname>URL</varname> key has to be
present when and only when when the value of the <varname>Type</varname>
key is <constant>Link</constant>.
</para>
<para>
Some example keys: <varname>Name[C]</varname>, <varname>Comment[it]</varname>.
</para>
<table>
<title>Standard Keys</title>
<tgroup cols="5">
<thead>
<row>
<entry>Key</entry>
<entry>Description</entry>
<entry>Value Type</entry>
<entry>REQ?</entry>
<entry>Type</entry>
</row>
</thead>
<tbody>
<row>
<entry id="key-type"><varname>Type</varname></entry>
<entry>
This specification defines 3 types of desktop entries:
<constant>Application</constant> (type 1),
<constant>Link</constant> (type 2)
and <constant>Directory</constant> (type 3).
To allow the addition of new types in the future,
implementations should ignore desktop entries with an
unknown type.
</entry>
<entry>string</entry>
<entry>YES</entry>
</row>
<row>
<entry id="key-version"><varname>Version</varname></entry>
<entry>
Version of the Desktop Entry Specification that the
desktop entry conforms with. Entries that confirm with this
version of the specification should use <literal>1.0</literal>.
Note that the version field is not required to be present.
</entry>
<entry>string</entry>
<entry>NO</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-name"><varname>Name</varname></entry>
<entry>
Specific name of the application, for example "Mozilla".
</entry>
<entry>localestring</entry>
<entry>YES</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-genericname"><varname>GenericName</varname></entry>
<entry>
Generic name of the application, for example "Web Browser".
</entry>
<entry>localestring</entry>
<entry>NO</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-nodisplay"><varname>NoDisplay</varname></entry>
<entry>
<varname>NoDisplay</varname> means "this application exists, but don't display it in the menus".
This can be useful to e.g. associate this application with MIME types, so that
it gets launched from a file manager (or other apps), without having a menu
entry for it (there are tons of good reasons for this, including e.g. the
<literal>netscape -remote</literal>, or <literal>kfmclient openURL</literal> kind of stuff).
</entry>
<entry>boolean</entry>
<entry>NO</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-comment"><varname>Comment</varname></entry>
<entry>
Tooltip for the entry, for example "View sites on the
Internet". The value should not be redundant with the values of
<varname>Name</varname> and <varname>GenericName</varname>.
</entry>
<entry>localestring</entry>
<entry>NO</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-icon"><varname>Icon</varname></entry>
<entry>
Icon to display in file manager, menus, etc. If the
name is an absolute path, the given file will be
used. If the name is not an absolute path, the algorithm described
in the <ulink
url="http://freedesktop.org/wiki/Standards/icon-theme-spec">Icon
Theme Specification</ulink> will be used to locate the icon.
</entry>
<entry>localestring</entry>
<entry>NO</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-hidden"><varname>Hidden</varname></entry>
<entry>
<varname>Hidden</varname> should have been called <varname>Deleted</varname>.
It means the user deleted (at his level)
something that was present (at an upper level, e.g. in the system dirs). It's
strictly equivalent to the <filename>.desktop</filename> file not existing at all, as far as that user is
concerned. This can also be used to "uninstall" existing files (e.g. due to a renaming)
- by letting <literal>make install</literal> install a file with <literal>Hidden=true</literal> in it.
</entry>
<entry>boolean</entry>
<entry>NO</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-onlyshowin"><varname>OnlyShowIn</varname>, <varname>NotShowIn</varname></entry>
<entry>
A list of strings identifying the environments that should
display/not display a given desktop entry. Only one of
these keys, either <varname>OnlyShowIn</varname> or
<varname>NotShowIn</varname>, may appear in a group (for
possible values see the <ulink
url="http://www.freedesktop.org/Standards/menu-spec">Desktop
Menu Specification</ulink>).
</entry>
<entry>string(s)</entry>
<entry>NO</entry>
<entry>1-3</entry>
</row>
<row>
<entry id="key-tryexec"><varname>TryExec</varname></entry>
<entry>
Path to an executable file on disk used to determine if the program
is actually installed. If the path is not an absolute path, the file
is looked up in the $PATH environment variable. If the file is not
present or if it is not executable, the entry may be ignored (not be
used in menus, for example).
</entry>
<entry>string</entry>
<entry>NO</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-exec"><varname>Exec</varname></entry>
<entry>
Program to execute, possibly with arguments.
</entry>
<entry>string</entry>
<entry>YES</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-path"><varname>Path</varname></entry>
<entry>
If entry is of type <constant>Application</constant>, the working directory to run the program in.
</entry>
<entry>string</entry>
<entry>NO</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-terminal"><varname>Terminal</varname></entry>
<entry>
Whether the program runs in a terminal window.
</entry>
<entry>boolean</entry>
<entry>NO</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-mimetype"><varname>MimeType</varname></entry>
<entry>
The MIME type(s) supported by this application.
</entry>
<entry>string(s)</entry>
<entry>NO</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-categories"><varname>Categories</varname></entry>
<entry>
Categories in which the entry should be shown in a menu (for
possible values see the <ulink
url="http://www.freedesktop.org/Standards/menu-spec">Desktop
Menu Specification</ulink>).
</entry>
<entry>string(s)</entry>
<entry>NO</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-startupnotify"><varname>StartupNotify</varname></entry>
<entry>
If true, it is KNOWN that the application will send a "remove"
message when started with the DESKTOP_STARTUP_ID environment variable set.
If false, it is KNOWN that the application does not work
with startup notification at all (does not shown any window, breaks
even when using StartupWMClass, etc.).
If absent, a reasonable handling is up to implementations (assuming false,
using StartupWMClass, etc.). (See the <ulink url="http://www.freedesktop.org/Standards/startup-notification-spec">Startup Notification Protocol Specification</ulink> for more details).
</entry>
<entry>boolean</entry>
<entry>NO</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-startupwmclass"><varname>StartupWMClass</varname></entry>
<entry>
If specified, it is known that the application will map at least one
window with the given string as its WM class or WM name hint (see the <ulink url="http://www.freedesktop.org/Standards/startup-notification-spec">Startup Notification Protocol Specification</ulink> for more details).
</entry>
<entry>string</entry>
<entry>NO</entry>
<entry>1</entry>
</row>
<row>
<entry id="key-url"><varname>URL</varname></entry>
<entry>
If entry is Link type, the URL to access.
</entry>
<entry>string</entry>
<entry>YES</entry>
<entry>2</entry>
</row>
</tbody>
</tgroup>
</table>
</sect1>
<sect1 id="exec-variables">
<title>The <varname>Exec</varname> key</title>
<para>
The <varname>Exec</varname> key must contain a command line.
A command line consists of an executable program optionally followed
by one or more arguments.
The executable program can either be specified with its full path or
with the name of the executable only. If no full path is provided the
executable is looked up in the $PATH environment variable used by the
desktop environment.
The name or path of the executable program may not contain the equal
sign ("="). Arguments are separated by a space.
</para>
<para>
Arguments may be quoted in whole. If an argument contains a reserved
character the argument must be quoted. The rules for quoting of
arguments is also applicable to the executable name or path of the
executable program as provided.
</para>
<para>
Quoting must be done by enclosing the argument between double quotes
and escaping the double quote character, backtick character ("`"),
dollar sign ("$") and backslash character ("\") by preceding it with an
additional backslash character. Implementations must undo quoting before
expanding field codes and before passing the argument to the executable
program. Reserved characters are space (" "), tab, newline, double
quote, single quote ("'"), backslash character ("\"),
greater-than sign (">"), less-than sign ("<"),
tilde ("~"), vertical bar ("|"), ampersand ("&"), semicolon (";"),
dollar sign ("$"), asterisk ("*"), question mark ("?"), hash mark ("#"),
parenthesis ("(") and (")") and backtick character ("`").
</para>
<para>
Note that the general escape rule for values of type string states that
the backslash character can be escaped as ("\\") as well and that this
escape rule is applied before the quoting rule. As such, to
unambiguously represent a literal backslash character in a quoted
argument in a desktop entry file requires the use of four successive
backslash characters ("\\\\"). Likewise, a literal dollar sign in a
quoted argument in a desktop entry file is unambiguously represented
with ("\\$").
</para>
<para>
A number of special field codes have been defined which will be
expanded by the file manager or program launcher when encountered
in the command line.
Field codes consist of the percentage character ("%") followed by
an alpha character. Literal percentage characters must be escaped
as <literal>%%</literal>.
Deprecated field codes should be removed from the command line and
ignored.
Field codes are expanded only once, the string that is used to
replace the field code should not be checked for field codes itself.
</para>
<para>
Command lines that contain a field code that is not listed in this
specification are invalid and must not be processed, in particular
implementations may not introduce support for field codes not listed
in this specification. Extensions, if any, should be introduced by
means of a new key.
</para>
<para>
Implementations must take care not to expand field codes into multiple
arguments unless explicitly instructed by this specification.
This means that name fields, filenames and other replacements that
can contain spaces must be passed as a single argument
to the executable program after expansion.
</para>
<para>
Although the <varname>Exec</varname> key is defined to have a value
of the type string, which is limited to ASCII characters, field code
expansion may introduce non-ASCII characters in arguments.
Implementations must take care that all characters in arguments
passed to the executable program are properly encoded according to
the applicable locale setting.
</para>
<para>
Recognized field codes are as follows:
</para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>Code</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>%f</literal></entry>
<entry>
A single file name, even if multiple files are selected. The system
reading the desktop entry should recognize that the program in
question cannot handle multiple file arguments, and it should
should probably spawn and execute multiple copies of a program
for each selected file if the program is not able to handle
additional file arguments. If files are not on the local file system
(i.e. are on HTTP or FTP locations), the files will be copied to the local
file system and <literal>%f</literal> will be expanded to point at the temporary
file. Used for programs that do not understand the URL syntax.
</entry>
</row>
<row>
<entry><literal>%F</literal></entry>
<entry>
A list of files. Use for apps that can open several local
files at once.
Each file is passed as a separate argument to
the executable program.
</entry>
</row>
<row>
<entry><literal>%u</literal></entry>
<entry>
A single URL. Local files may either be passed as
file: URLs or as file path.
</entry>
</row>
<row>
<entry><literal>%U</literal></entry>
<entry>
A list of URLs.
Each URL is passed as a separate argument to
the executable program. Local files may either be passed as
file: URLs or as file path.
</entry>
</row>
<row>
<entry><literal>%d</literal></entry>
<entry>
Deprecated.
</entry>
</row>
<row>
<entry><literal>%D</literal></entry>
<entry>
Deprecated.
</entry>
</row>
<row>
<entry><literal>%n</literal></entry>
<entry>
Deprecated.
</entry>
</row>
<row>
<entry><literal>%N</literal></entry>
<entry>
Deprecated.
</entry>
</row>
<row>
<entry><literal>%i</literal></entry>
<entry>
The <varname>Icon</varname> key of the desktop entry
expanded as two arguments, first
<literal>--icon</literal> and then the value of the
<varname>Icon</varname> key. Should not expand to any
arguments if the <varname>Icon</varname> key is empty
or missing.
</entry>
</row>
<row>
<entry><literal>%c</literal></entry>
<entry>
The translated name of the application as listed in
the appropriate <varname>Name</varname> key in the
desktop entry.
</entry>
</row>
<row>
<entry><literal>%k</literal></entry>
<entry>
The location of the desktop file as either a URI (if for
example gotten from the vfolder system) or a local
filename or empty if no location is known.
</entry>
</row>
<row>
<entry><literal>%v</literal></entry>
<entry>
Deprecated.
</entry>
</row>
<row>
<entry><literal>%m</literal></entry>
<entry>
Deprecated.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>
A command line may contain at most one %f, %u, %F or %U field code.
If the application should not open any
file the %f, %u, %F and %U field codes must be removed from the
command line and ignored.
</para>
<para>
Field codes must not be used inside a quoted argument, the result of
field code expansion inside a quoted argument is undefined. The %F and
%U field codes may only be used as an argument on their own.
</para>
</sect1>
<sect1 id="mime-types">
<title>Registering MIME Types</title>
<para>
The <varname>MimeType</varname> key is used to indicate the MIME
Types that an application knows how to handle. It is expected that
for some applications this list could become long. An application
is expected to be able to reasonably open files of these types
using the command listed in the <varname>Exec</varname> key.
</para>
<para>
There should be no priority for MIME Types in this field, or any
form of priority in the desktop file. Priority for applications
is handled external to the <filename>.desktop</filename> files.
</para>
<!--
<sect2 id="mime-caching">
<title>Caching MIME Types</title>
<para>
To make parsing of all the desktop files less costly, a
<command>update-desktop-database</command> program is provided
that will generate a cache file. The concept is identical to
that of the 'update-mime-database' program in that it lets
applications avoid reading in (potentially) hundreds of files.
It will need to be run after every desktop file is installed.
One cache file is created for every directory in
$XDG_DATA_DIRS/applications/, and will create a file called
$XDG_DATA_DIRS/applications/mimeinfo.cache.
</para>
<para>
The format of the cache is similar to that of the desktop file,
and is just a list mapping mime-types to desktop files. Here's
a quick example of what it would look like:
</para>
<programlisting>application/x-foo=foo.desktop;bar.desktop;
application/x-bar=bar.desktop;</programlisting>
<para>
Each MIME Type is listed only once per cache file, and the
desktop-id is expected to exist in that particular directory.
That is to say, if the cache file is located at
<filename>/usr/share/applications/mimeinfo.cache</filename>,
bar.desktop refers to the file
<filename>/usr/share/applications/bar.desktop</filename>.
</para>
</sect2>
<sect2 id="mime-priority">
<title>Priority of MIME Types and desktop files</title>
<para>
There is also a preference list to determine preferred
application of a given MIME Type. It defines the 'default'
application to handle a given MIME Type. It has the same format
as the cache list.
</para>
<programlisting>mime/type=desktop-id.desktop;</programlisting>
<para>
If a mime type is listed multiple times (either in the same
file, or in another file further down the search path), the
latter mention wins. If a listed file doesn't exist, or is
precluded through the <varname>OnlyShowIn</varname> or
<varname>NotShowIn</varname> keys, they should be ignored.
This means that applications will have to keep a history of the
preferred applications that they run into, so that if the top
desktop file for a given MIME Type isn't available, the second
one can be tested, etc.
</para>
<para>
It is also worth noting who this mechanism is defined for. It
is primarily intended for use by distributors/sysadmins to
provide a sane set of defaults for their users. Additionally,
users themselves can use this mechanism to override the user
defaults. We intentionally don't provide a way for application
authors themselves to list themselves as the default for a given
type, as we felt that that cannot work.
</para>
</sect2>
-->
</sect1>
<sect1 id="extending">
<title>Extending the format</title>
<para>
If the standard is to be amended with a new <literal>{key,value}</literal> pair which
should be applicable to all supporting parties, a group discussion
will take place. This is the preferred method for introducing
changes. If one particular party wishes to add a field for personal
use, they should prefix the key with the string <varname>X-<replaceable>PRODUCT</replaceable></varname>,
e.g. <varname>X-NewDesktop-Foo</varname>, following the precedent set by other IETF and RFC
standards.
</para>
<para>
Alternatively, fields can be placed in their own group, where they may
then have arbitrary key names. If this is the case, the group should
follow the scheme outlined above,
i.e. <literal>[X-<replaceable>PRODUCT</replaceable>
<replaceable>GROUPNAME</replaceable>]</literal> or
something similar. These steps will avoid namespace clashes between
different yet similar environments.
</para>
</sect1>
<appendix id="example">
<title>Example Desktop Entry File</title>
<programlisting>
[Desktop Entry]
Version=1.0
Type=Application
Name=Foo Viewer
Comment=The best viewer for Foo objects available!
TryExec=fooview
Exec=fooview %F
Icon=fooview
MimeType=image/x-foo;
X-KDE-Library=libfooview
X-KDE-FactoryName=fooviewfactory
X-KDE-ServiceType=FooService</programlisting>
</appendix>
<appendix id="kde-items">
<title>Currently reserved for use within KDE</title>
<para>
For historical reasons KDE is using some KDE-specific extensions
that are currently not prefixed by a <literal>X-KDE-</literal> prefix.
</para>
<itemizedlist>
<listitem>
<para>
KDE specific keys: <varname>ServiceTypes</varname>,
<varname>DocPath</varname>, <varname>Keywords</varname>,
<varname>InitialPreference</varname>
</para>
</listitem>
<listitem>
<para>
KDE specific types: <constant>ServiceType</constant>,
<constant>Service</constant> and <constant>FSDevice</constant>
</para>
</listitem>
</itemizedlist>
<para>
KDE uses the following additional keys for desktop entries of the
<constant>FSDevice</constant> type.
</para>
<table>
<title>FSDevice Specific Keys</title>
<tgroup cols="3">
<thead>
<row>
<entry>Key</entry>
<entry>Description</entry>
<entry>Value Type</entry>
</row>
</thead>
<tbody>
<row>
<entry id="key-dev"><varname>Dev</varname></entry>
<entry>
The device to mount.
</entry>
<entry>string</entry>
</row>
<row>
<entry id="key-fstype"><varname>FSType</varname></entry>
<entry>
The type of file system to try to mount.
</entry>
<entry>string</entry>
</row>
<row>
<entry id="key-mountpoint"><varname>MountPoint</varname></entry>
<entry>
The mount point of the device in question.
</entry>
<entry>string</entry>
</row>
<row>
<entry id="key-readonly"><varname>ReadOnly</varname></entry>
<entry>
Specifies whether or not the device is read only.
</entry>
<entry>boolean</entry>
</row>
<row>
<entry id="key-unmounticon"><varname>UnmountIcon</varname></entry>
<entry>
Icon to display when device is not mounted. Mounted devices display icon from the <varname>Icon</varname> key.
</entry>
<entry>localestring</entry>
</row>
</tbody>
</tgroup>
</table>
</appendix>
<appendix id="deprecated-items">
<title>Deprecated Items</title>
<para>
As this standard is quite old there are some deprecated items that
may or may not be used by several implementations.
</para>
<itemizedlist>
<listitem>
<para>
<literal>Type=MimeType</literal> is deprecated as there is a
new standard for this now, see the <ulink
url="http://www.freedesktop.org/Standards/shared-mime-info-spec">Shared
MIME-info Database specification</ulink> for more
information. In consequence the Keys
<varname>Patterns</varname> (various file name extensions
associated with the MIME type) and
<varname>DefaultApp</varname> (the default application
associated with this MIME type) are also deprecated.
</para>
</listitem>
<listitem>
<para>
Using <filename>.kdelnk</filename> instead of
<filename>.desktop</filename> as the file extension is
deprecated.
</para>
</listitem>
<listitem>
<para>
Using <literal>[KDE Desktop Entry]</literal> instead of
<literal>[Desktop Entry]</literal> as header is deprecated.
</para>
</listitem>
<listitem>
<para>
The <literal>Encoding</literal> key is deprecated. It was used to
specify whether keys of type <literal>localestring</literal> were
encoded in UTF-8 or in the specified locale. Possible values are
<literal>UTF-8</literal> and <literal>Legacy-Mixed</literal>. See
<xref linkend="legacy-mixed"/> for more details.
</para>
</listitem>
<listitem>
<para>
Deprecated <varname>Exec</varname> field codes:
<literal>%m</literal> (the mini-icon associated with the
desktop entry, this should be expanded as two arguments,
<literal>--miniicon</literal> and the content of the
<varname>MiniIcon</varname> key, it can also be ignored by
expanding it to no arguments), %v (the device as listed
in the <varname>Dev</varname> key in the desktop file),
%d (the directory of a file), %D (the directories of
files), %n (the base name of a file) and %N (the base names
of files).
</para>
</listitem>
<listitem>
<para>
Deprecated keys: <varname>MiniIcon</varname> (small icon for
menus, etc.), <varname>TerminalOptions</varname> (if the
program runs in a terminal, any options that should be
passed to the terminal emulator before actually executing
the program), <varname>Protocols</varname>,
<varname>Extensions</varname>,
<varname>BinaryPattern</varname>,
<varname>MapNotify</varname>.
</para>
</listitem>
<listitem>
<para>
The <literal>SwallowTitle</literal> and
<literal>SwallowExec</literal> keys are deprecated.
The <literal>SwallowTitle</literal> key is of type
<literal>localestring</literal> and specifies the title of the window
if is swallowed onto the panel. The <literal>SwallowExec</literal>
key is of type <literal>string</literal> and specifies the
program to exec if swallowed app is clicked.
</para>
</listitem>
<listitem>
<para>
The <literal>SortOrder</literal> key is deprecated. It is of type
<literal>string(s)</literal> and may be used to specify the order in
which to display files. The <ulink
url="http://www.freedesktop.org/Standards/menu-spec">Desktop
Menu Specification</ulink> defines another mechanism for defining the
order of menu items.
</para>
</listitem>
<listitem>
<para>
The <literal>FilePattern</literal> key is deprecated.
The value is a list of regular
expressions to match against for a file manager to determine if this
entry's icon should be displayed. Usually simply the name of the main
executable and friends.
</para>
</listitem>
<listitem>
<para>
Historically some booleans have been represented by the numeric
entries <constant>0</constant> or <constant>1</constant>. With
this version of the standard they are now to be represented as a
boolean string. However, if an implementation is reading a pre-1.0
desktop entry, it should interpret <constant>0</constant> and
<constant>1</constant> as <constant>false</constant> and
<constant>true</constant>, respectively.
</para>
</listitem>
<listitem>
<para>
Historically lists have been comma separated. This is inconsistent with other lists which are separated by a semicolon. When reading a pre-1.0 desktop entry, comma separated lists should continue to be supported.
</para>
</listitem>
</itemizedlist>
</appendix>
<appendix id="legacy-mixed">
<title>The <constant>Legacy-Mixed</constant> Encoding (Deprecated)</title>
<para>
The <constant>Legacy-Mixed</constant> encoding corresponds to the
traditional encoding of desktop files in older versions of the GNOME and
KDE desktop files. In this encoding, the encoding of each
<literal>localestring</literal> key is determined by the locale tag for
that key, if any, instead of being UTF-8. For keys without a locale tag,
the value must contain only ASCII characters.
</para>
<para>
If the file specifies an unsupported encoding, the implementation
should either ignore the file, or, if the user has requested a direct
operation on the file (such as opening it for editing), display an
appropriate error indication to the user.
</para>
<para>
In the absence of an <varname>Encoding</varname> key, the implementation may choose
to autodetect the encoding of the file by using such factors
as:
</para>
<itemizedlist>
<listitem>
<para>
The location of the file on the file system
</para>
</listitem>
<listitem>
<para>
Whether the contents of the file are valid UTF-8
</para>
</listitem>
</itemizedlist>
<para>
If the implementation does not perform such auto-detection, it should
treat a file without an <varname>Encoding</varname> key in the same way as a file with an
unsupported <varname>Encoding</varname> key.
</para>
<para>
If the locale tag includes an <literal>.<replaceable>ENCODING</replaceable></literal> part, then that determines
the encoding for the line. Otherwise, the encoding is determined
by the language, or
<literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>
pair from the locale tag, according to the following table.
</para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>Encoding</entry>
<entry>Aliases</entry>
<entry>Tags</entry>
</row>
</thead>
<tbody>
<row>
<entry>ARMSCII-8 (*)</entry><entry></entry><entry>hy</entry>
</row><row>
<entry>BIG5</entry><entry></entry><entry>zh_TW</entry>
</row><row>
<entry>CP1251</entry><entry></entry><entry>be bg</entry>
</row><row>
<entry>EUC-CN</entry><entry>GB2312</entry><entry>zh_CN</entry>
</row><row>
<entry>EUC-JP</entry><entry></entry><entry>ja</entry>
</row><row>
<entry>EUC-KR</entry><entry></entry><entry>ko</entry>
</row><row>
<entry>GEORGIAN-ACADEMY (*)</entry><entry></entry><entry></entry>
</row><row>
<entry>GEORGIAN-PS (*)</entry><entry></entry><entry>ka</entry>
</row><row>
<entry>ISO-8859-1</entry><entry></entry><entry>br ca da de en es eu fi fr gl it nl no pt sv wa</entry>
</row><row>
<entry>ISO-8859-2</entry><entry></entry><entry>cs hr hu pl ro sk sl sq sr</entry>
</row><row>
<entry>ISO-8859-3 </entry><entry></entry><entry>eo</entry>
</row><row>
<entry>ISO-8859-5</entry><entry></entry><entry>mk sp</entry>
</row><row>
<entry>ISO-8859-7</entry><entry></entry><entry>el</entry>
</row><row>
<entry>ISO-8859-9</entry><entry></entry><entry>tr</entry>
</row><row>
<entry>ISO-8859-13</entry><entry></entry><entry>lt lv mi</entry>
</row><row>
<entry>ISO-8859-14</entry><entry></entry><entry>cy ga</entry>
</row><row>
<entry>ISO-8859-15</entry><entry></entry><entry>et</entry>
</row><row>
<entry>KOI8-R</entry><entry></entry><entry>ru</entry>
</row><row>
<entry>KOI8-U</entry><entry></entry><entry>uk</entry>
</row><row>
<entry>TCVN-5712 (*)</entry><entry>TCVN</entry><entry>vi</entry>
</row><row>
<entry>TIS-620</entry><entry></entry><entry>th</entry>
</row><row>
<entry>VISCII</entry><entry></entry><entry></entry>
</row>
</tbody>
</tgroup>
</informaltable>
<variablelist>
<varlistentry>
<term>Encoding</term>
<listitem>
<para>
The name given here is listed here is typically the
canonical name for the encoding in the GNU C Library's
<function>iconv</function> facility. Encodings marked with (*) are not
currently supported by the GNU C Library; for this reason,
implementations may choose to ignore lines in desktop
files that resolve to this encoding. Desktop files with
these encodings are currently rare or non-existent.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Aliases</term>
<listitem>
<para>
Other names for the encoding found in existing desktop
files.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Tags</term>
<listitem>
<para>
Language tags for which this is the default encoding.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
This table above covers all tags and encodings that are known to
be currently in use. Implementors may choose to support
encodings not in the above set. For tags without defaults listed
in the above table, desktop file creators must specify the
<literal>.<replaceable>ENCODING</replaceable></literal> part of the locale tag.
</para>
<para>
Matching the <literal>.<replaceable>ENCODING</replaceable></literal> part of the locale tag against a locale
name or alias should be done by stripping all punctuation
characters from both the tag and the name or alias, converting
both name and alias to lowercase, and comparing the result.
This is necessary because, for example, <literal>Big5</literal> is frequently
found instead of <literal>BIG5</literal> and <literal>georgianacademy</literal> instead of
<literal>GEORGIAN-ACADEMY</literal>. Desktop files creators should, however, use
the name as it appears in the "Encoding" column above.
</para>
</appendix>
</article>
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