Linux.Desktop.Hacks [Electronic resources] نسخه متنی

Hack 40. Create Your Own KDE Right-Click Menu Actions

Create custom menu actions for when you
right-click a file, directory, or group of files and/or directories.

When you use KDE, do you ever
find
yourself having to click too many times to do a simple operation, or
resort to opening up a terminal to do a task at the command line that
should have been a no-brainer feature of KDE? Now you can add your
own features to KDE context menus. Right-click a file and click
ActionMake Executable to make the file executable.
Right-click an empty space in a folder and click
ActionCreate a new Bash Script to open an editor and fill
in the first line. This is a very cool hack because you can create a
context menu to launch scripts or programs written in any language.
It is especially powerful if you learn DCOP scripting [Hack #39] . That way you can use the
context menu selection to control KDE programs.

Remember all the times you wrote a dandy new bash script and created
an icon to launch it, but when you clicked it, it
didn't run? Instead, it popped up in an editor,
because you forgot to make the script executable. With this hack, you
can create a script to make your file executable by right-clicking
its icon and selecting ActionsMake file executable (see
Figure 5-4). It takes much less time than
traditional methods.

All you have to do to create the context menu that will make a file
executable is create a text file formatted very much like an
application link, and then drop it in a special directory.
We'll start by creating a file called
make_executable.desktop. Start up your favorite
editor, and enter the following text:

[Desktop Entry]
Encoding=UTF-8
ServiceTypes=application/x-shellscript
Actions=MakeExe
[Desktop Action MakeExe]
Name=Make file executable
Exec=chmod +x %f
Icon=kfm

Save your work. The action this file takes is defined by the entry
Exec=chmod +x
%f. KDE substitutes the name of the selected file
for %f. If you want to make this feature available
to everyone who uses KDE on this computer, place the file here:

# cp make_executable.desktop <path to kde> 
/share/apps/konqueror/servicemenus

Depending on your Linux distribution, the path might not be tied to
your KDE directory. It might be
/usr/share/apps/konqueror/servicemenus.

If you simply want to make this feature available to yourself, place
the file here (assuming your KDE settings are kept in
~/.kde; your distribution might use
~/.kde3.3 or something similar):

$ cp make_executable.desktop ~/.kde/share/apps/konqueror/servicemenus

The ServiceTypes field in the file is set to the mime-type application/x-shellscript, which means the menu option will be available only when you right-click a shell script file.

Figure 5-4. Context-sensitive Actions menu

5.7.1. Symbols Available for Menu Actions

Konqueror passes the names of selected URLs, selected files, and
other selected elements to your custom menu actions through the use
of symbols. Symbols exist for single files, multiple files, single
URLs, and more. The right-click action that allows you to change a
file to be executable works, because it substitutes the name of the
selected file for the symbol %f. Here are some
other symbols available to you, and how they work.

%f

A single filename, even if you select multiple files. In general, you
use this only when you intend to select a single file. In some cases,
you can use this to select several files for use by a program that
knows how to launch a separate instance for each filename.

%F

Multiple selected files. Use this for programs that can act upon
several files at once.

%u

A single URL.

%U

Multiple URLs.

%d

The single directory that contains the selected file represented by
%f.

%D

A list of the same directory containing an entry for every selected
file in that directory (%F).

%n

A filename without a path.

%N

Multiple filenames without paths.

%k

A file represented as a URI.

5.7.2. Create an Action to Jump-Start Script Writing

Here's another hack to give you
a
taste of some of the power behind KDE custom menus. This time, you
will exploit three powerful features of KDE. The first is the ability
to create submenus. You will create a general menu selection that
lets you choose between two actions that appear as submenus. The
second is the fact that your custom action can be a script instead of
a simple command, such as the chmod
+x command we used in the previous example.
Finally, the script will exploit the ability to use DCOP to
manipulate KDE applications [Hack #39] .

To get started, create the file
/usr/local/bin/CreateBashScript.desktop. Use
your favorite editor to put the following contents into that file:

[Desktop Entry]
ServiceTypes=inode/directory
Actions=CreateBashScript;CreatePythonScript
X-KDE-Submenu=Create Script
[Desktop Action CreateBashScript]
Name=Create a bash script
Icon=kfm
Exec=/usr/local/bin/writeBashScript
[Desktop Action CreatePythonScript]
Name=Create a Python script
Icon=kfm
Exec=/usr/local/bin/writePythonScript

In this case, the ServiceTypes definition of
inode/directory tells KDE that the submenu entry
Create Script will appear under
the Action menu selection only if you are pointing to a folder or to
an empty area within the Konqueror file manager (which represents the
currently open folder). When you select this action, it will give you
the choice of creating a bash or Python script. If you choose
ActionCreate ScriptCreate a bash script, it will
launch the shell script
/usr/local/bin/writeBashScript. Use your
favorite editor with sudo (or log in as root) to
create the writeBashScript file, with the
following contents:

#!/bin/bash
cd ~/bin
kwrite &
sleep 2
kwid=`dcop | grep kwrite | sort | tail -n 1`
echo $kwid
dcop $kwid EditInterface#1 insertText 0 0 '#!/bin/bash'
dcop $kwid EditInterface#1 insertLine 1 ''
dcop $kwid EditInterface#1 insertLine 2 ''
dcop $kwid ViewCursorInterface#1-1 setCursorPosition 2 0

Here's how it works. First, it changes to the
user's directory where the user keeps his personal
~/bin scripts. This is totally arbitrary, and it
assumes you want to place all your personal shell scripts in this
directory. Replace this directory with whatever directory you prefer
(and one to which you have read, write, and execute access). Then it
launches kwrite followed by an ampersand to let
it run in the background while the
writeBashScript shell script finishes. Again,
the use of kwrite is arbitrary, but it is a good
example of how to use DCOP to automate actions, because it is a
KDE editor with DCOP capabilities. Then the script sleeps for 2
seconds (you can set this to a higher number if your system is always
slow and busy) to make sure kwrite is running
before it starts issuing DCOP commands to it.

The next line is a bit tricky. Each time you launch an instance of
kwrite, it gets a DCOP listing with a number
attached to it. You want to address the most recently launched copy
of kwrite, so the script runs
dcop to list all DCOP applications, finds all
the applications that match
"kwrite," sorts the list, and picks
the last entry. That entry's name is assigned to the
variable $kwid. This works even if this is the
first instance of kwrite you have launched.

Then the script issues a few DCOP instructions. It automatically
enters the first line of a typical bash script,
#!/bin/bash, after which it enters two more
blank lines and moves the cursor to the last blank line.

Now create the bash script that gets you started writing a Python
script. The only difference between
/usr/local/bin/writeBashScript and
/usr/local/bin/writePythonScript is that you
will insert the first line as the full path to your Python
interpreter instead of #!/bin/bash. That line of
code should look like this:

dcop $kwid EditInterface#1 insertText 0 0 '#!/usr/bin/python'

Obviously, there's no limit to the kinds of
templates you can create for various scripting languages.

These examples barely scratch the surface of what you can do. You can
create a single menu entry that lets you select a half dozen
directories, tar and compress them, and burn them to a multisession
CD, all in one fell swoop. And you have the flexibility to do this as
a bash script, as a Python script, or in any method you prefer.
You'll be surprised at how much more you rely on the
GUI interface of KDE once you have customized menu features for your
personal convenience.