beginning Ubuntu Linux phần 5 pot

And while traditionally text files were managed with command-line tools and text editors, the focus of this chapter is on introducing graphical tools such as gedit.. ■ Tip Most program R

Type of Program Windows Ubuntu Alternative Choices

www.abisource comwww.koffice.org/kword

www.gnome.org/projects/ gnumeric

www.koffice.org/kspread

www.koffice.org/kpresenter

www.inkscape.org

www koffice org/karbon

www.knoda.org

http://kompozer.net/www.w3.org/Amaya

www.mozilla.comhttp://kontact.kde.org/kmailwww.kontact.kde.org

www.konqueror.org

www.google.com/chromewww.twotoasts.de

www.opera.comwww.k3b.org

http://aqualung.factorial hu

http://banshee-project.org

CHAPTER 11 A WORLD OF APPLICATIONS

http://nostatic.org/grip

www.videolan.orgwww.mplayerhq.hu/homepage

www.koffice.org/krita

www.kdenlive.org

orange.fr/coquelle/karchiver cmd.exe

http://pagesperso-command.exe

www.x.org

www.kate-editor.org

xterm

LINUX HAS IT ALL

The Ubuntu software archives contain thousands of programs to cover just about every task you mightwant to accomplish on your computer Diversity is vitally important within the Linux world For example,rather than just one e-mail program, you’ll find many available They compete with each other in a gentleway, and it’s up to you which one you settle down with and use

Part of the fun of using Linux is exploring what’s available Of course, the added bonus is that virtually allthis software is free of charge, so you can simply download, install, and play around If you don’t like aprogram, just remove it from your system However, don’t forget to revisit the program’s home page after

a few months; chances are the program will have been expanded and improved in that short period, and itmight be better at meeting your needs

A Quick Start with Common Ubuntu Programs

CHAPTER 11 A WORLD OF APPLICATIONS

Figure 11-1 OpenOffice.org Writer



Note OpenOffice.org is covered in more detail in Chapter 13

Tip In all the OpenOffice.org applications, you can hover the mouse cursor over each button for one second to

see a tooltip showing what it does

CHAPTER 11 A WORLD OF APPLICATIONS

Figure 11-2 OpenOffice.org Calc



Figure 11-3 OpenOffice.org Impress

CHAPTER 11 A WORLD OF APPLICATIONS

.ppt.swf





Figure 11-4 OpenOffice.org Base

CHAPTER 11 A WORLD OF APPLICATIONS

Figure 11-5 Evolution

Figure 11-6 Mozilla Firefox

Tip When Firefox starts, tabs aren’t activated If you would like to keep tabs in view all the time, click Edit 

Preferences, click the Tabs button, and then put a check alongside Always Show the Tab Bar

CHAPTER 11 A WORLD OF APPLICATIONS

Note Unlike iTunes, Rhythmbox can’t play Digital Rights Management (DRM)-protected files, including standard

tracks bought through the iTunes Music Store iTunes, Amazon.com, and others offer music not encumbered withDRM, and these, as well as music you’ve ripped from CDs, will play perfectly

CHAPTER 11 A WORLD OF APPLICATIONS

Figure 11-8 Totem movie player



Tip Most modern CD/DVD recorders utilize burn-proof technology, which helps ensure error-free disc creation

To activate this for the Nautilus CD/DVD Creator, open a terminal window (Applications  Accessories  Terminal)

check in Search Also in Key Names In the search results at the bottom of the window, click the first result (/apps/nautilus-cd-burner/burnproof) and make sure there’s a check in burnproof at the top right of the window Then close the configuration editor

Figure 11-9 Nautilus CD/DVD Creator and Brasero

CHAPTER 11 A WORLD OF APPLICATIONS



Figure 11-10 GIMP

Other Handy Applications

Figure 11-11 GNOME Calculator

CHAPTER 11 A WORLD OF APPLICATIONS

Figure 11-12 Archive Manager

Collaborative International

Dictionary



Figure 11-13 Dictionary



CHAPTER 11 A WORLD OF APPLICATIONS

Figure 11-14 Empathy



Figure 11-15 Ekiga





CHAPTER 11 A WORLD OF APPLICATIONS

Figure 11-16 Mines

www.winehq.org

Figure 11-17 Wine

Summary

C H A P T E R 12

■ ■ ■

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Working with Text Files

Windows views text files as just another file type, but to Ubuntu (and to the whole Linux family in fact), they are the very fabric of which the system is made Configuration files and program documentation are stored as plain text This is clearly different from Windows, where any information you’re supposed to

read will likely be contained in a Windows help file, a rich text format (RTF) file, or even a Microsoft

Word document

So important are text files to Linux that for a long time you could have been caught in a heated

debate over which text editor was the best! And while traditionally text files were managed with

command-line tools and text editors, the focus of this chapter is on introducing graphical tools such as gedit No doubt one day you will get to grips with command-line text editors such as Vim, Emacs, or

even both—but right now the thing is to get you up and running with Lucid Lynx!

It’s worth mentioning that text files under Linux usually don’t have a file extension Unlike with

Windows or other OSs, the txt file extension is rarely used Sometimes a conf extension is added to

plain text configuration files, but more often text files have no extension at all

Text: A History Lesson

Given this reliance on text and text files, it has always been very important for Linux administrators and power users alike to have powerful text-manipulation tools at their fingertips

■ Tip Most program README files, along with other assorted documentation, can be found in a directory named

Piping and Redirecting

When you execute a command in a terminal window (which was—and for many people still is—an

everyday task), output is usually produced in the form of a text stream So the same techniques that

apply to text files can be also used on this output, with a simple operation called piping Piping is the

process of sending the output of a command as the input for another command, usually a

text-manipulation tool That output is then manipulated as if it were a file Powerful!

We’ll illustrate this with an example using grep grep is a tool that takes text as its input, searches

and tries to match a regular expression or piece of text, and prints the lines that contain that regular

266

through Applications ➤ Accessories ➤ Terminal):

grep Linux operatingsystems.txt

grep will look for the text “Linux” in the file operatingsystems.txt and print only the lines that contain that text So grep works with text files to filter lines in a file based on criteria you set

But what if you want to do the same thing not to a text file, but to the output of a command? You use piping, which is expressed by the character | It instructs a command to send its output to another command (and to the second command to take that as its input) For example, if you want to find a particular process—say, the process gedit (processes are listed with the ps command)—you’d type the following at the command line:

ps -d | grep gedit

This command will show you information about the gedit process (if it is running)

Another way of attaining a similar end is by means of redirecting—expressed with the character >

Redirecting means sending the output of a command to a text file So the preceding task could be fulfilled by executing two commands: one for listing process information (and redirecting its output) and the other to display only the lines that pertain to a certain process:

ps -d > processes.txt

grep gedit processes.txt

STANDARD INPUT AND OUTPUT

If you’ve read any of the Ubuntu man pages, you might have seen references to standard input and

standard output Like many things in Linux, this sounds complicated, but is merely a long-winded way of referring to something that is relatively simple (although the terms have specific meanings to

programmers) Standard input is simply the device that programs running under Ubuntu normally take input from In other words, on the majority of desktop PCs, when you’re using the command-line shell, standard input refers to the keyboard However, it’s important to note that it could also refer to the mouse

or any other device on your system capable of providing input; even some software can take the role of providing standard input

Standard output is similar It refers to the device to which output from a command is usually sent from software In the majority of cases at the command line, this refers to the monitor screen, although it could

be any kind of output device, such as your PC’s sound card and speakers

In other words, for the majority of desktop Ubuntu installations, it will combine (concatenate) any number

of files together and print the results on the screen If you specify just one file, it will display that single file

CHAPTER 12 ■ WORKING WITH TEXT FILES

grep The grep command searches for regular expressions or text patterns in a text file or

command output, and prints only matching lines The name is derived from

“global/regular expression/print.” Use grep if you want to filter lines based on the

presence of a word

sed Short for “stream editor,” as its name implies, this transforms a text stream based on

specified rules and criteria Use sed if you want to search and replace a word in a text file or modify the output of a command

awk AWK, whose name derives from the family names of its creators (Alfred Aho, Peter

Weinberger, and Brian Kernighan), is a powerful text-manipulation programming

language As Alfred Aho puts it, “AWK is a language for processing files of text A file is

treated as a sequence of records, and by default each line is a record Each line is broken up into a sequence of fields, so we can think of the first word in a line as the first field, the

second word as the second field, and so on An AWK program is of a sequence of

pattern-action statements AWK reads the input a line at a time A line is scanned for each pattern in the program, and for each pattern that matches, the associated action is executed.” It is

used, for example, to print specified columns of a text file

cat This is a UNIX command used to display and concatenate text files You can, for example,

merge two text files into a third file

head This is used to display just the first lines of a text file

tail This is used to display just the last few lines of a text file

more This is a command-line utility used to display the contents of a text file one screen at a

time

less This command lets you move backward in the document

sort This tool is used to sort the lines in a text file or stream in forward or reverse order

diff This tool is used to compare two text files and print the differences between them It’s

useful if you are comparing, for example, two versions of the same source code

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■ Note The less and more commands are sometimes known as pagers because of their ability to let you scroll

through pages of text You might still hear them referred to as such in the wider Linux community, although the term has fallen out of use

Bash is an incredibly capable tool when it comes to text manipulation, and some of its tool set offers modest word processing–like functionality It’s no wonder that some people live their lives working at the Bash prompt and have no need of sophisticated GUI tools!

Table 12-2 lists some more text-processing tools that you can use on the command line Along with the commands are listed any command options needed to make them work in a useful way Some commands rely on redirection and piping, which were explained earlier in this chapter

■ Note Most text-processing tools under Bash were created for programmers, so some options might seem a little

odd when you read the man pages However, all the tools are extremely flexible and offer functions for every kind

of user

Table 12-2 Useful Text-Processing Commands

Spell-check aspell -c filename Highlights any questionable words within filename, and

offers a choice of replacements, rather like a standard word processor’s spell-checker Press X if you wish to exit after spell-checking starts

Single word

spell-check

look word Looks up word in the dictionary; if the word is displayed in

the output, the word has been found If not, the word hasn’t been found Note that this command returns loose matches—searching for test, for example, will return every word beginning with test (testing, testimony, testosterone, and so forth)

Word count wc -w filename Outputs the number of words in filename Used without

the -w command switch, wc outputs the number of lines, followed by the word count, followed by the number of bytes in the file

Remove line

breaks fmt filename > newfile Creates newfile, removing breaks at the ends of lines in

filename Double line breaks between paragraphs aren’t

affected Adding the -u command switch removes instances of double spaces too

CHAPTER 12 ■ WORKING WITH TEXT FILES

269

Join two files paste file1 file2 >

file3 Creates file3 by joining file1 and file2 side by side

(effectively creating two columns of text) Each line is separated by a tab

Word wrap fold -sw20 filename >

newfile

Creates newfile from filename, wrapping lines at the

specified 20 characters (increase/decrease this value for shorter/longer lines) Note that the -s switch ensures that lines don’t break across words, even if this means exceeding the specified character count

Add line

numbers nl filename > newfile Creates newfile from filename, adding line numbers to

the beginning of each line

Sort list sort file1 > file2 Creates file2 from file1, sorting its contents

alphanumerically (technically, it sorts according to ASCII,

so some symbols appear above numbers) For obvious reasons, this command works best on lists

If none of this makes sense to you, it doesn’t matter, because you will seldom need to use this

knowledge for everyday tasks But it is an interesting insight to know that there’s more to Linux than

meets the eye!

The Text Editor Wars

A variety of text editors can be used within the shell, but three stand out as being ubiquitous: ed, Vim,

and Emacs The first in that list, ed, is by far the simplest That doesn’t necessarily mean that it’s simple

to use or lacks powerful features, but it just doesn’t match the astonishing power of both Vim and

Emacs To call Vim and Emacs simple text editors is to do them a disservice, because both are extremely powerful interactive environments In particular, Emacs is considered practically an OS in itself, and

some users of Linux treat it as their shell, executing commands and performing everyday tasks, such as reading and sending e-mail from within it There are entire books written solely about Emacs and Vim

■Tip A fourth shell-based text editor found on many Linux systems is nano This offers many word processor–like

features that can be helpful if you’ve come to Linux from a Windows background

The downside of all the power within Emacs and Vim is that both packages can be difficult to learn

to use They’re considered idiosyncratic by even their most ardent fans Both require the user to learn

certain unfamiliar concepts, as well as keyboard shortcuts and commands

Although there are debates about which text editor is better and which is best, it’s generally agreed that Vim offers substantial text-editing power but isn’t too all-encompassing It’s also installed by default

on Ubuntu On Ubuntu, Emacs must be installed as an optional extra Both text editors are normally

available on virtually every installation of Linux or UNIX We’ll concentrate on using Vim here

270

there are many versions and updates of vi The original program, once supplied with UNIX, is rarely used

nowadays Vim is the most commonly used clone; Vim stands for vi improved Another version is elvis

(http://elvis.the-little-red-haired-girl.org) However, most people still refer to Vim and elvis as vi, even though they are entirely new pieces of software

■ Note There used to be a constant flame war between advocates of vi and Emacs, as to which was better This

could be quite a vicious and desperate debate, and the text editor you used was often taken as a measure of your character! Nowadays, the battle between the two camps has softened, and the Emacs vs vi debate is considered

an entertaining cliché of Linux and UNIX use When users declare online which text editor they prefer, they often include a smiley symbol to acknowledge the once-fevered emotions

Working with Text Files

Fortunately, you don’t need to learn how to use those tools if you don’t feel like it, because Ubuntu

comes equipped with a powerful, and yes, graphical, text-editing tool: gedit gedit is in fact the default

text editor for the GNOME desktop environment, so you can find it in other distributions of Linux such

as Fedora and SUSE

Introducing gedit

The basic interface of gedit, as you can see in Figure 12-1, is quite similar of that of Notepad, and in many regards the two applications work very much alike But gedit has some salient features, such as plug-in support, that raise it above the crowd of simple text-editing tools like Notepad You’ll see that there are a lot of available plug-ins for gedit that will enable you to do things you can only dream of doing with other text editors In this respect, it is a tool that honors the history of Linux; it isn’t just a simple GUI replacement for Vim or Emacs

CHAPTER 12 ■ WORKING WITH TEXT FILES

271

Figure 12-1 gedit: A simple yet powerful graphical text editor

One of the neat features is the ability to work with tabs, just like in your favorite web browser Each

tab is an open text file So when you are, for example, writing a script or taking notes, you can have Don Quixote, the classic novel by Spanish writer Miguel de Cervantes Saavedra, open in another tab to take

short breaks from work!

The gedit window has the following elements:

Menubar: The menubar gives you access to all gedit commands

Toolbar: Using the toolbar you can perform common tasks such as creating, opening, and saving

text files

Display area: The display area is where the action is! This is where the text is actually displayed

Statusbar: The statusbar, shown at the bottom of the window, displays information about current

activity and contextual menus

Side Pane: The side pane displays a list of open documents, and other information depending on

which plug-ins are enabled By default, the side pane is not shown To show it, choose View ➤

Side Pane

272

By default, the bottom pane is not shown To show it, choose View ➤ Bottom Pane

To start gedit, simply go to Applications ➤ Accessories ➤ gedit Text Editor, or right-click a text file and select “Open with gedit.” It is also very likely that if you double-click a text file it will automatically

be opened with gedit

Opening gedit with those methods assumes that you will edit the file with your everyday user account But what if you want to edit a configuration file to which only superusers have access? Normal users will only be able to open it in read-only mode, meaning that they will be unable to save the

changes they make To edit configuration files, press Alt+F2 to invoke the Run Command dialog box and

type gksu gedit in the text field After entering your password, gedit will open with root-like privileges

The basic operations are simply explained You have the buttons on the toolbar and the options in the menus To create a new file, just click File ➤ New, and a new tab will be created with a blank

document (the same happens if you click the New button on the toolbar) To open an existing file, click File ➤ Open…, and a dialog box will let you browse for the text file to open Finally, click File ➤ Save to store the results of your work to the disk

Once you have the desired file in your display area, you can begin to work as with any text editor You can write new text, select chunks of text and copy it to the clipboard, or paste text from other sources You cannot apply formatting to parts of the file, since gedit is only a text editor, not a word processing tool such as OpenOffice.org’s Writer What you save are text files, and because of this gedit is fully interoperable with Notepad

gedit saves the history of recently opened files, which you can see by expanding the File menu or clicking the small arrow next to the Open button in the toolbar If you click a file, it will open once again

Working with gedit

Working with gedit is just a matter of entering text in the display area and saving the file from time to time While simple, it does offer plenty of options that can make your tasks easier and more enjoyable The menubar gives you access to all the operations that can be performed with gedit Table 12-3 lists all the options available in the menubar You can open a test file and play a little with those options to familiarize yourself with them You can also use the Personalize dialog box to modify the program’s general behavior

Table 12-3 The Menubar Options

File New Creates a new text file from scratch

Open… Allows you to browse your disk and open an existing text file

Save Stores the changes you have made to the file on the disk You need to

have write permissions on the file to do this

Save As… Allows you to save your file with a different name or to an alternate

location It’s useful if you don’t have write permissions on the file or if want to save several versions of the same file

Revert Undoes all changes made to the document since the last time you

saved it

CHAPTER 12 ■ WORKING WITH TEXT FILES

273

Print Preview Displays how the document will be printed As this is not a word

processor, there wouldn’t be much surprises here, but at least you would

be able to anticipate how many pages the document has

Print… Actually prints the file

List of files Lists the recently opened files Click a file to open it again

Close Closes only the current document You will be asked whether you want to

save it beforehand

Quit Quits gedit All documents can be saved beforehand

Edit Undo Undoes the last change

Redo Redoes the last undone change

Cut Copies the selected text to the clipboard and deletes it from the file

Copy Copies the selected text to the clipboard without deleting it from the file Paste Inserts the contents of the clipboard into the current file

Delete Deletes the selected text from the file without copying it to the clipboard Select All Selects all text in the file so you can later copy, cut, or delete it

Preferences Gives you access to the Preferences dialog box (explained later in this

chapter)

View Toolbar Shows or hides the toolbar It is selected by default

Statusbar Shows or hides the statusbar It is selected by default

Side Pane Shows or hides the side pane It is disabled by default

Bottom Pane Shows or hides the bottom pane It is disabled and grayed out by default

Some programming functions will allow you to enable it

Fullscreen Switches to full-screen mode for easier editing Change back to normal