1. Table of Contents Beginning Linux Programming, Second Edition.............................................................................................1 Foreword..............................................................................................................................................................5 Introduction.........................................................................................................................................................6 Welcome.................................................................................................................................................6 Who's this Book For?..............................................................................................................................6 What's Covered in the Book...................................................................................................................6 What You Need to Use this Book...........................................................................................................8 Source Code............................................................................................................................................9 Conventions............................................................................................................................................9 Tell Us What You Think.......................................................................................................................10 Why Should I Return the Reply Card?.................................................................................................10 Chapter 1: Getting Started.............................................................................................................................11 Overview...............................................................................................................................................11 What is UNIX?.....................................................................................................................................11 What is Linux?......................................................................................................................................11 Distributions..........................................................................................................................................11 The GNU Project and the Free Software Foundation...........................................................................12 Programming Linux..............................................................................................................................13 UNIX Programs....................................................................................................................................13 The C Compiler..............................................................................................................................14 Try It Out Our First UNIX C Program........................................................................................14 How It Works..................................................................................................................................15 Getting Help..........................................................................................................................................15 Try It Out Manual Pages and info................................................................................................16 Development System Roadmap............................................................................................................17 Programs.........................................................................................................................................17 Header Files....................................................................................................................................18 Library Files...................................................................................................................................19 Static Libraries...............................................................................................................................19 Try It Out Static Libraries............................................................................................................20 Shared Libraries.............................................................................................................................22 UNIX Philosophy.................................................................................................................................23 Simplicity.......................................................................................................................................23 Focus..............................................................................................................................................23 Reusable Components....................................................................................................................23 Filters..............................................................................................................................................23 Open File Formats..........................................................................................................................23 Flexibility.......................................................................................................................................23 Summary...............................................................................................................................................24 Chapter 2: Shell Programming.......................................................................................................................25 Overview...............................................................................................................................................25 What is a Shell?....................................................................................................................................26 Pipes and Redirection...........................................................................................................................27 Redirecting Output.........................................................................................................................27 Redirecting Input............................................................................................................................28 Pipes...............................................................................................................................................28 i

2. Table of Contents Chapter 2: Shell Programming The Shell as a Programming Language................................................................................................29 Interactive Programs.......................................................................................................................29 Creating a Script.............................................................................................................................30 Making a Script Executable...........................................................................................................31 Shell Syntax..........................................................................................................................................32 Variables.........................................................................................................................................33 Conditions......................................................................................................................................36 Control Structures...........................................................................................................................38 Functions........................................................................................................................................49 Try It Out A Simple Function......................................................................................................50 How It Works..................................................................................................................................50 Try It Out Returning a Value.......................................................................................................51 How It Works..................................................................................................................................52 Commands......................................................................................................................................52 Command Execution......................................................................................................................62 Here Documents.............................................................................................................................66 Try It Out Using Here Documents...............................................................................................66 Try It Out Another Use for a Here Document.............................................................................67 How It Works..................................................................................................................................67 Debugging Scripts..........................................................................................................................67 Putting it All Together..........................................................................................................................68 Requirements..................................................................................................................................68 Design.............................................................................................................................................69 Try It Out A CD Application.......................................................................................................70 Notes................................................................................................................................................76 Summary...............................................................................................................................................77 Chapter 3: Working with Files.......................................................................................................................78 Overview...............................................................................................................................................78 UNIX File Structure..............................................................................................................................78 Directories......................................................................................................................................79 Files and Devices............................................................................................................................79 System Calls and Device Drivers.........................................................................................................81 Library Functions..................................................................................................................................82 Lowlevel File Access..........................................................................................................................82 write.................................................................................................................................................83 read..................................................................................................................................................83 open.................................................................................................................................................84 Initial Permissions...........................................................................................................................85 umask...............................................................................................................................................86 close.................................................................................................................................................87 ioctl..................................................................................................................................................87 Try It Out A File Copy Program..................................................................................................87 Other System Calls for Managing Files.........................................................................................89 The Standard I/O Library......................................................................................................................91 fopen................................................................................................................................................92 fread.................................................................................................................................................92 fwrite...............................................................................................................................................93 fclose...............................................................................................................................................93 ii 3. Table of Contents Chapter 3: Working with Files fflush................................................................................................................................................93 fseek.................................................................................................................................................93 fgetc, getc, getchar...........................................................................................................................94 fputc, putc, putchar..........................................................................................................................94 fgets, gets.........................................................................................................................................94 Formatted Input and Output...........................................................................................................95 Other Stream Functions..................................................................................................................98 Try It Out Another File Copy Program.......................................................................................99 Stream Errors..................................................................................................................................99 Streams and File Descriptors........................................................................................................100 File and Directory Maintenance..........................................................................................................101 chmod............................................................................................................................................101 chown............................................................................................................................................101 unlink, link, symlink......................................................................................................................101 mkdir, rmdir...................................................................................................................................102 chdir, getcwd.................................................................................................................................102 Scanning Directories...........................................................................................................................103 opendir...........................................................................................................................................103 readdir............................................................................................................................................103 telldir.............................................................................................................................................104 seekdir...........................................................................................................................................104 closedir..........................................................................................................................................104 Try It Out A Directory Scanning Program................................................................................105 How It Works................................................................................................................................106 Errors...................................................................................................................................................107 Advanced Topics................................................................................................................................107 fcntl................................................................................................................................................108 mmap.............................................................................................................................................109 Try It Out Using mmap.............................................................................................................110 Summary.............................................................................................................................................111 Chapter 4: The UNIX Environment............................................................................................................112 Overview.............................................................................................................................................112 Program Arguments............................................................................................................................112 Try It Out Program Arguments.................................................................................................113 How It Works................................................................................................................................114 getopt............................................................................................................................................114 Try It Out getopt.......................................................................................................................115 How It Works................................................................................................................................116 Environment Variables.......................................................................................................................116 Try It Out getenv and putenv0...................................................................................................117 Use of Environment Variables.....................................................................................................118 The environ Variable....................................................................................................................119 Try It Out environ......................................................................................................................119 How It Works................................................................................................................................119 Time and Date.....................................................................................................................................119 Try It Out time...........................................................................................................................120 How It Works................................................................................................................................121 Try It Out gmtime.....................................................................................................................121 iii 4. Table of Contents Chapter 4: The UNIX Environment How It Works................................................................................................................................122 Try It Out ctime.........................................................................................................................123 How It Works................................................................................................................................123 Try It Out strftime and strptime................................................................................................125 How It Works................................................................................................................................126 Temporary Files..................................................................................................................................126 Try It Out tmpnam and tmpfile.................................................................................................127 How It Works................................................................................................................................127 User Information.................................................................................................................................128 Try It Out User Information.......................................................................................................129 How It Works................................................................................................................................130 Other User Information Functions...............................................................................................130 Host Information.................................................................................................................................131 Try It Out Host Information.......................................................................................................131 How It Works................................................................................................................................132 Licensing......................................................................................................................................132 Logging...............................................................................................................................................132 Try It Out syslog........................................................................................................................134 How It Works................................................................................................................................134 Configuring Logs.........................................................................................................................134 Try It Out logmask.....................................................................................................................135 How It Works................................................................................................................................136 Resources and Limits..........................................................................................................................136 Try It Out Resource Limits.......................................................................................................138 How It Works................................................................................................................................140 Summary.............................................................................................................................................140 Chapter 5: Terminals....................................................................................................................................141 Overview.............................................................................................................................................141 Reading from and Writing to the Terminal.........................................................................................141 Try It Out Menu Routines in C..................................................................................................141 How It Works................................................................................................................................142 Why It Doesn't Quite Work...........................................................................................................143 Handling Redirected Output.........................................................................................................144 Try It Out Checking for Output Redirection..............................................................................144 How It Works................................................................................................................................145 Talking to the Terminal................................................................................................................145 Try It Out Using /dev/tty............................................................................................................146 The Terminal Driver and the General Terminal Interface..................................................................147 Overview......................................................................................................................................147 Hardware Model...........................................................................................................................148 The termios Structure..........................................................................................................................149 Input Modes..................................................................................................................................150 Output Modes...............................................................................................................................151 Control Modes..............................................................................................................................152 Local Modes.................................................................................................................................152 Special Control Characters...........................................................................................................153 Terminal Speed.............................................................................................................................156 Additional Functions....................................................................................................................156 iv 5. Table of Contents Chapter 5: Terminals Try It Out A Password Program with termios...........................................................................157 How It Works................................................................................................................................158 Try It Out Reading Each Character............................................................................................158 How It Works................................................................................................................................159 Terminal Output..................................................................................................................................159 Terminal Type..............................................................................................................................159 Identify Your Terminal Type.......................................................................................................160 Using terminfo Capabilities..........................................................................................................162 Detecting Keystrokes..........................................................................................................................167 Try It Out Your Very Own kbhit...............................................................................................167 How It Works................................................................................................................................169 Pseudo Terminals.........................................................................................................................169 Summary.............................................................................................................................................169 Chapter 6: Curses..........................................................................................................................................170 Overview.............................................................................................................................................170 Compiling with curses........................................................................................................................170 Concepts..............................................................................................................................................171 Try It Out A Simple curses Program.........................................................................................172 Initialization and Termination.............................................................................................................173 Output to the Screen............................................................................................................................173 Reading from the Screen.....................................................................................................................174 Clearing the Screen.............................................................................................................................175 Moving the Cursor..............................................................................................................................175 Character Attributes............................................................................................................................175 Try It Out Moving, Inserting and Attributes..............................................................................176 The Keyboard......................................................................................................................................177 Keyboard Modes..........................................................................................................................177 Keyboard Input.............................................................................................................................178 Try It Out Keyboard Modes and Input........................................................................................178 How It Works................................................................................................................................179 Windows.............................................................................................................................................180 The WINDOW Structure..............................................................................................................180 Generalized Functions..................................................................................................................180 Moving and Updating a Window.................................................................................................181 Try It Out Multiple Windows....................................................................................................182 Optimizing Screen Refreshes.......................................................................................................184 Subwindows........................................................................................................................................185 Try It Out Subwindows..............................................................................................................185 How It Works................................................................................................................................187 The Keypad.........................................................................................................................................187 Try It Out Using the Keypad.....................................................................................................188 Color...................................................................................................................................................189 Try It Out Colors.......................................................................................................................190 Redefining Colors.........................................................................................................................191 Pads.....................................................................................................................................................191 Try It Out Using a Pad...............................................................................................................192 The CD Collection Application..........................................................................................................193 Try It Out A New CD Collection Application...........................................................................194 v 6. Table of Contents Chapter 6: Curses Try It Out Looking at main........................................................................................................196 Try It Out The Menu..................................................................................................................196 Try It Out Database File Manipulation.....................................................................................198 Try It Out Querying the CD Database.......................................................................................202 Summary.............................................................................................................................................206 Chapter 7: Data Management......................................................................................................................207 Overview.............................................................................................................................................207 Managing Memory..............................................................................................................................207 Simple Memory Allocation..........................................................................................................207 Try It Out Simple Memory Allocation......................................................................................208 How It Works................................................................................................................................208 Allocating Lots of Memory..........................................................................................................208 Try It Out Asking for all Physical Memory..............................................................................209 How It Works................................................................................................................................209 Try It Out Available Memory....................................................................................................210 How It Works................................................................................................................................210 Abusing Memory..........................................................................................................................211 Try It Out Abuse Your Memory................................................................................................211 How It Works................................................................................................................................212 The Null Pointer...........................................................................................................................212 Try It Out Accessing a Null Pointer..........................................................................................212 How It Works................................................................................................................................213 How It Works................................................................................................................................213 Freeing Memory...........................................................................................................................213 Try It Out Freeing Memory.......................................................................................................214 How It Works................................................................................................................................214 Other Memory Allocation Functions...........................................................................................214 File Locking........................................................................................................................................215 Creating Lock Files......................................................................................................................215 Try It Out Creating a Lock File.................................................................................................216 How It Works................................................................................................................................216 Try It Out Cooperative Lock Files............................................................................................217 How It Works................................................................................................................................218 Locking Regions...........................................................................................................................218 Use of read and write with Locking.............................................................................................221 Try It Out Locking a File with fcntl...........................................................................................221 How It Works................................................................................................................................222 Try It Out Testing Locks on a File.............................................................................................223 How It Works................................................................................................................................225 Competing Locks.........................................................................................................................226 Try It Out Competing Locks.....................................................................................................226 How It Works................................................................................................................................228 Other Lock Commands................................................................................................................228 Deadlocks.....................................................................................................................................229 Databases............................................................................................................................................229 The dbm Database........................................................................................................................229 The dbm Routines........................................................................................................................230 dbm Access Functions..................................................................................................................232 vi 7. Table of Contents Chapter 7: Data Management Additional dbm Functions............................................................................................................235 The CD Application............................................................................................................................237 The CD Application Using dbm...................................................................................................238 Try It Out cd_data.h...................................................................................................................238 Try It Out app_ui.c.....................................................................................................................239 Try It Out cd_access.c...............................................................................................................247 Summary.............................................................................................................................................253 Chapter 8: Development Tools.....................................................................................................................254 Overview.............................................................................................................................................254 Problems of Multiple Source Files.....................................................................................................254 The make Command and Makefiles...................................................................................................255 The Syntax of Makefiles..............................................................................................................255 Options and Parameters to make..................................................................................................255 Comments in a makefile...............................................................................................................258 Macros in a makefile....................................................................................................................258 Try It Out A Makefile with Macros...........................................................................................259 How It Works................................................................................................................................259 Multiple Targets...........................................................................................................................260 Try It Out Multiple Targets........................................................................................................260 How It Works................................................................................................................................262 Builtin Rules..............................................................................................................................262 Suffix Rules..................................................................................................................................263 Try It Out Suffix Rules..............................................................................................................263 How It Works................................................................................................................................264 Managing Libraries with make.....................................................................................................264 Try It Out Managing a Library..................................................................................................264 How It Works................................................................................................................................265 Advanced Topic: Makefiles and Subdirectories..........................................................................266 GNU make and gcc......................................................................................................................266 Try It Out gcc MM...................................................................................................................267 How It Works................................................................................................................................267 Source Code Control...........................................................................................................................267 RCS..............................................................................................................................................267 SCCS............................................................................................................................................273 CVS..............................................................................................................................................274 Writing a Manual Page.......................................................................................................................278 Distributing Software..........................................................................................................................281 The patch Program.......................................................................................................................281 Other Distribution Utilities...........................................................................................................283 Summary.............................................................................................................................................285 Chapter 9: Debugging....................................................................................................................................286 Types of Error.....................................................................................................................................286 Specification Errors......................................................................................................................286 Design Errors................................................................................................................................286 Coding Errors...............................................................................................................................286 General Debugging Techniques..........................................................................................................287 A Program with Bugs...................................................................................................................287 vii 8. Table of Contents Chapter 9: Debugging Code Inspection............................................................................................................................289 Instrumentation.............................................................................................................................290 Try It Out Debug Information....................................................................................................291 How It Works................................................................................................................................291 Controlled Execution....................................................................................................................292 Debugging with gdb............................................................................................................................293 Starting gdb..................................................................................................................................293 Running a Program.......................................................................................................................294 Stack Trace...................................................................................................................................294 Examining Variables....................................................................................................................295 Listing the Program......................................................................................................................296 Setting Breakpoints......................................................................................................................296 Patching with the Debugger.........................................................................................................299 Learning more about gdb.............................................................................................................300 More Debugging Tools.......................................................................................................................300 Lint: Removing the Fluff from Your Programs...........................................................................301 Function Call Tools......................................................................................................................302 Execution Profiling.......................................................................................................................304 Assertions............................................................................................................................................304 Problems with assert.....................................................................................................................305 Try It Out assert........................................................................................................................305 How It Works................................................................................................................................306 Memory Debugging............................................................................................................................306 ElectricFence................................................................................................................................307 Try It Out ElectricFence............................................................................................................307 How It Works................................................................................................................................308 Checker.........................................................................................................................................308 Try It Out Checker.....................................................................................................................308 How It Works................................................................................................................................309 Resources............................................................................................................................................310 Summary.............................................................................................................................................310 Chapter 10: Processes and Signals...............................................................................................................311 Overview.............................................................................................................................................311 What is a Process?..............................................................................................................................311 Process Structure.................................................................................................................................311 The Process Table........................................................................................................................313 Viewing Processes........................................................................................................................313 System Processes..........................................................................................................................314 Process Scheduling.......................................................................................................................315 Starting New Processes.......................................................................................................................316 Try It Out system.......................................................................................................................316 How It Works................................................................................................................................317 Replacing a Process Image............................................................................................................317 Try It Out execlp.......................................................................................................................318 How It Works................................................................................................................................319 Duplicating a Process Image.........................................................................................................319 Try It Out fork...........................................................................................................................320 How It Works................................................................................................................................321 viii 9. Table of Contents Chapter 10: Processes and Signals Waiting for a Process...................................................................................................................321 Try It Out wait............................................................................................................................322 How It Works................................................................................................................................323 Zombie Processes.........................................................................................................................323 Try It Out Zombies....................................................................................................................324 How It Works................................................................................................................................324 Input and Output Redirection.......................................................................................................325 Try It Out Redirection...............................................................................................................325 How It Works................................................................................................................................326 Threads.........................................................................................................................................326 Signals.................................................................................................................................................326 Try It Out Signal Handling.......................................................................................................328 How It Works................................................................................................................................329 Sending Signals............................................................................................................................330 Try It Out An Alarm Clock........................................................................................................330 How It Works................................................................................................................................331 Signal Sets....................................................................................................................................334 Summary.............................................................................................................................................337 Chapter 11: POSIX Threads.........................................................................................................................338 What is a Thread?...............................................................................................................................338 Advantages and Drawbacks of Threads.......................................................................................338 Checking for Thread Support..............................................................................................................339 Try it out POSIX compliance test..............................................................................................339 How it works.................................................................................................................................340 A First Threads Program.....................................................................................................................340 Try it out a simple threaded program.........................................................................................342 How it works.................................................................................................................................343 Simultaneous Execution.....................................................................................................................344 Try it out simultaneous execution of two threads......................................................................344 How it works.................................................................................................................................345 Synchronization..................................................................................................................................345 Synchronization with Semaphores...............................................................................................345 Try it out a thread semaphore....................................................................................................347 How it works.................................................................................................................................349 Synchronization with Mutexes.....................................................................................................350 Try it out a thread mutex............................................................................................................350 How it works.................................................................................................................................352 Thread Attributes................................................................................................................................353 detachedstate.................................................................................................................................354 schedpolicy....................................................................................................................................354 schedparam....................................................................................................................................355 inheritsched...................................................................................................................................355 scope..............................................................................................................................................355 stacksize.........................................................................................................................................355 Try it out setting the detached state attribute.............................................................................355 How it works.................................................................................................................................356 Thread Attributes Scheduling....................................................................................................357 Try is out scheduling..................................................................................................................357 ix 10. Table of Contents Chapter 11: POSIX Threads How it works.................................................................................................................................357 Canceling a Thread.............................................................................................................................357 Try it out canceling a thread......................................................................................................358 How it works.................................................................................................................................360 Threads in Abundance........................................................................................................................360 Try it out many threads..............................................................................................................360 How it works.................................................................................................................................362 Summary.............................................................................................................................................363 Chapter 12: Interprocess Communication: Pipes....................................................................................364 Overview.............................................................................................................................................364 What is a Pipe?....................................................................................................................................364 Process Pipes.......................................................................................................................................365 popen.............................................................................................................................................365 pclose.............................................................................................................................................365 Try It Out Reading Output From an External Program............................................................365 How It Works................................................................................................................................366 Sending Output to popen..............................................................................................................366 Try It Out Sending Output to an External Program...................................................................366 How It Works................................................................................................................................367 The Pipe Call......................................................................................................................................369 Try It Out The pipe Function.....................................................................................................370 How It Works................................................................................................................................371 Try It Out Pipes across a fork...................................................................................................371 How It Works................................................................................................................................372 Parent and Child Processes.................................................................................................................372 Try It Out Pipes and exec...........................................................................................................372 How It Works................................................................................................................................373 Reading Closed Pipes...................................................................................................................374 Pipes Used as Standard Input and Output....................................................................................374 Named Pipes: FIFOs...........................................................................................................................377 Try It Out Creating a Named Pipe.............................................................................................378 How It Works................................................................................................................................378 Accessing a FIFO.........................................................................................................................378 Try It Out Accessing a FIFO File.............................................................................................379 How It Works................................................................................................................................379 Advanced Topic: Client/Server using FIFOs......................................................................................385 Try It Out An Example Client/Server Application...................................................................385 How It Works................................................................................................................................388 The CD Application............................................................................................................................388 Aims.............................................................................................................................................389 Implementation.............................................................................................................................390 Try It Out The Header File, cliserv.h.........................................................................................392 Client Interface Functions............................................................................................................393 Try It Out The Client's Interpreter.............................................................................................393 The Server Interface.....................................................................................................................399 Try It Out server.c......................................................................................................................399 The Pipe........................................................................................................................................402 Try It Out Pipes Implementation Header...................................................................................402 x 11. Table of Contents Chapter 12: Interprocess Communication: Pipes Application Summary...................................................................................................................407 Summary.............................................................................................................................................407 Chapter 13: Semaphores, Message Queues and Shared Memory.............................................................409 Semaphores.........................................................................................................................................409 Semaphore Definition...................................................................................................................410 A Theoretical Example.................................................................................................................410 UNIX Semaphore Facilities.........................................................................................................411 Using Semaphores........................................................................................................................413 Try It Out Semaphores...............................................................................................................414 How It Works................................................................................................................................416 Semaphore Summary...................................................................................................................417 Shared Memory...................................................................................................................................417 Overview......................................................................................................................................417 Shared Memory Functions...........................................................................................................418 Shared Memory Summary............................................................................................................423 Message Queues..................................................................................................................................423 Overview......................................................................................................................................424 Message Queue Functions............................................................................................................424 Message Queue Summary............................................................................................................429 The Application..................................................................................................................................429 Try It Out Revising the Server Functions..................................................................................429 Try It Out Revising the Client Functions...................................................................................431 IPC Status Commands........................................................................................................................433 Semaphores..................................................................................................................................433 Shared Memory............................................................................................................................433 Message Queues...........................................................................................................................433 Summary.............................................................................................................................................434 Chapter 14: Sockets.......................................................................................................................................435 Overview.............................................................................................................................................435 What is a Socket?................................................................................................................................435 Socket Connections.............................................................................................................................435 Try It Out A Simple Local Client..............................................................................................436 Try It Out A Simple Local Server.............................................................................................437 Socket Attributes..........................................................................................................................439 Creating a Socket..........................................................................................................................441 Socket Addresses..........................................................................................................................442 Naming a Socket..........................................................................................................................442 Creating a Socket Queue..............................................................................................................443 Accepting Connections.................................................................................................................443 Requesting Connections...............................................................................................................444 Closing a Socket...........................................................................................................................445 Socket Communications...............................................................................................................445 Try It Out Network Client..........................................................................................................446 How It Works................................................................................................................................446 Try It Out Network Server........................................................................................................446 How It Works................................................................................................................................447 Host and Network Byte Ordering.................................................................................................447 xi 12. Table of Contents Chapter 14: Sockets Network Information..........................................................................................................................449 Try It Out Network Information...............................................................................................450 How It Works................................................................................................................................451 Try It Out Connecting to a Standard Service............................................................................452 How It Works................................................................................................................................453 The Internet Daemon....................................................................................................................453 Socket Options.............................................................................................................................454 Multiple Clients..................................................................................................................................454 Try It Out A Server for Multiple Clients...................................................................................455 How It Works................................................................................................................................457 select...................................................................................................................................................457 Try It Out select.........................................................................................................................458 How It Works................................................................................................................................460 Multiple Clients............................................................................................................................460 Try It Out An Improved Multiple Client/Server........................................................................460 Summary.............................................................................................................................................463 Chapter 15: Tcl: Tool Command Language...............................................................................................464 Overview.............................................................................................................................................464 A Tcl Overview...................................................................................................................................464 Our First Tcl Program..................................................................................................................464 Tcl Commands.............................................................................................................................465 Variables and Values....................................................................................................................466 Quoting and Substitution..............................................................................................................467 Calculation....................................................................................................................................470 Control Structures.........................................................................................................................471 Error Handling..............................................................................................................................473 String Operations..........................................................................................................................474 Arrays...........................................................................................................................................479 Lists..............................................................................................................................................481 Procedures....................................................................................................................................486 Try It Out Procedures................................................................................................................486 How It Works................................................................................................................................487 Input and Output...........................................................................................................................487 A Tcl Program.....................................................................................................................................491 Try It Out A Concordance Program...........................................................................................491 How It Works................................................................................................................................493 Network Support...........................................................................................................................493 Try It Out socket.......................................................................................................................494 How It Works................................................................................................................................494 Creating a New Tcl.............................................................................................................................494 Tcl Extensions.....................................................................................................................................494 expect............................................................................................................................................494 [incr Tcl].......................................................................................................................................495 TclX..............................................................................................................................................495 Graphics........................................................................................................................................495 Summary.............................................................................................................................................495 xii 13. Table of Contents Chapter 16: Programming for X..................................................................................................................496 Overview.............................................................................................................................................496 What is X?...........................................................................................................................................496 X Server.........................................................................................................................................497 X Protocol......................................................................................................................................497 Xlib................................................................................................................................................497 X Clients........................................................................................................................................497 X Toolkits.....................................................................................................................................497 X Window Manager............................................................................................................................498 The X Programming Model................................................................................................................499 Start Up.........................................................................................................................................499 Main Loop....................................................................................................................................500 Clean Up.......................................................................................................................................500 Fast Track X Programming.................................................................................................................501 The Tk Toolkit....................................................................................................................................501 Windows Programming................................................................................................................502 Try It Out Saying Hello.............................................................................................................503 How It Works................................................................................................................................503 Configuration Files.......................................................................................................................504 More Commands..........................................................................................................................504 Tk Widgets...................................................................................................................................505 Try It Out Learning More..........................................................................................................505 How It Works................................................................................................................................506 Tk's Builtin Dialogs...................................................................................................................529 Color Chooser................................................................................................................................529 Get Open/Save Files......................................................................................................................530 Color Schemes..............................................................................................................................531 Fonts.............................................................................................................................................532 Bindings........................................................................................................................................532 BindTags......................................................................................................................................533 Geometry Management................................................................................................................535 Focus and Navigation...................................................................................................................537 Option Database...........................................................................................................................538 Interapplication Communication................................................................................................539 Selection.......................................................................................................................................539 Clipboard......................................................................................................................................540 Window Manager.........................................................................................................................541 Dynamic/Static Loading...............................................................................................................542 Safe Tk.........................................................................................................................................543 A MegaWidget.................................................................................................................................544 Package File Generation................................................................................................................553 An Application Using the Tree MegaWidget...................................................................................554 Tk Process Log Viewer.......................................................................................................................556 Internationalization.......................................................................................................................566 Where Now?.................................................................................................................................567 Tix.................................................................................................................................................567 [incr Tk].........................................................................................................................................567 BLT...............................................................................................................................................567 Summary.............................................................................................................................................568 xiii 14. Table of Contents Chapter 17: Programming GNOME using GTK+.....................................................................................569 Overview.............................................................................................................................................569 An Introduction to GNOME...............................................................................................................569 The GNOME Architecture...........................................................................................................570 The GNOME Desktop..................................................................................................................571 Programming in GNOME using GTK+.......................................................................................572 An Application in GNOME.........................................................................................................586 Summary.............................................................................................................................................594 Chapter 18: The Perl Programming