TUI completed

gdb-tui.txt

@@ -0,0 +1,287 @@
+Section 6: GDB Text User Interface (TUI):
+-----------------------------------------
+
+-> GDB the Text User Interface (TUI):
+   +++++++++++++++++++++++++++++++++
+
+   To run gdb along with the source code for easy analysis
+   along the program execution in CLI, we can use TUI.
+
+   * To open gdb along with TUI...
+
+        Command:
+        $ gdb --tui ./<program-name>
+
+   * If gdb is already in execution and to open source code for
+     when there is already a program which is being debugged.
+
+        Command:
+        (gdb) layout src
+
+        Note:
+            To checkout what other things layout command perform.
+
+            (gdb) help layout
+
+        Keybindings:
+        To cycle through various layout we use.
+
+        Key-Bind:
+        CTRL + x -- 2
+
+    * To navigate through windows if there is different window
+      present, for example, having source code and GDB CLI
+      window, we can use:
+
+      Key-Bind:
+      CTRL + x -- o
+
+    * To achieve the same feat without using this key binds and
+      using only commands, we can use:
+
+      Command:
+      (gdb) focus cmd   -> To focus to gdb CLI
+        
+        OR
+
+      (gdb) focus src   -> To focus on source code.
+      
+        
+        Note:
+        If the focus is on source window and we want to
+        navigate to previous or next command on gdb CLI.
+
+        We can use:
+
+        Key-binds:
+
+        CTRL + p    -> To previous command
+        CTRL + n    -> To next command
+
+    * To resize the windows, we can use:
+
+      Command:
+      (gdb) winheight <window-name>  <value by which we to change the size>
+
+        For ex:
+        (gdb) winheight src -2
+
+            To shrink the size of source window by 2.
+          
+
+    Note:
+
+    Sometimes while executing some command our screen gets
+    messed up due the execution of program which is being
+    debugged. To clear the mess and make it look clean
+    we can use..
+
+    Command:
+    (gdb) refresh 
+
+    Key-bind:
+    CTRL + l
+
+
+-> Redirecting output from GDB (to another file or terminal):
+   ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+    *  While analysing the program under gdb with TUI, executing
+       commands can mess up the UI making it sometime frustrating
+       to debug. Instead, we can redirect the output of the
+       program in gdb to other terminal using...
+
+        
+        Command:
+        tty
+            (Remember to type this command in another terminal.
+
+       To allow the output to be redirected from gdb to the terminal
+       where the above command is executed we can use...
+
+       Command:
+       (gdb)tty /dev/pts/<num>
+
+       Now because of the above operation all the gdb output will
+       be redirected to the other intended terminal.
+
+    * If we want to capture the content to a file and save we can
+      use command:
+
+      Command:
+      (gdb)run > <filename> 
+
+-> Conditional Breakpoints:
+   ++++++++++++++++++++++++
+
+   * There are 2 types of breakpoints that we have learnt till
+     now and that are:
+     1. Temporary breakpoint
+            Stop the execution only once.
+
+     2. breakpoint (permanent breakpoint)
+            Stop the execution each time the breakpoint got hit
+            and remains until the current gdb session or explicitly
+            deleted.
+
+     There is another type of breakpoint that we can use.
+     
+     ==Conditional breakpoint==
+
+     This breakpoint will stop the execution only when certain
+     condition that we define is met.
+
+
+        Command:
+        br <line-number> if <conditions>
+
+            The <conditions> should follow the C syntax.
+
+            For ex:
+
+            br 9 if i > 343 
+                Where i is some variable which is present in
+                the source.
+
+    Note:
+        
+        To delete any breakpoint of any type use...
+        Command:
+
+        delete <num>
+            where <num> is the index number of breakpoints
+            when we print the list of breakpoint using 
+            command >>> info breakpoint <<<
+
+
+-> More ways to continue and step through code (advance, and until):
+   +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 
+
+
+   Command:
+   (gdb)advance <args>
+        Here, <args> can be function name, line numbers.
+
+   * This command is used to advance our program execution till certain points.
+
+   Command:
+   (gdb)until <args>
+        Here, <args> can be numbers.
+
+    * This command will execute the program until we reach the location which
+      is passed as an argument to the command.
+
+   Command:
+   (gdb)jump <args>
+
+        Here, <args> is a address.
+
+    * This is helpful in terms of asm code and we can jump to certain location
+      in code, directly. However, giving random address will give output that
+      no function is defined in this address and providing illegal address 
+      leads to crash in program.
+
+-> Watching (watch and rwatch) Variables:
+   ++++++++++++++++++++++++++++++++++++++ 
+    
+    These are great tools to inspect the memory locations and break the execution
+    when there is a read or write operation performed on these memory locations.
+
+    Command:
+    (gdb)watch <expr>
+        where <expr> can be a variable name.
+
+        This command is used to watch a memory location when there is a change
+        or write operation is performed in it.
+
+    (gdb)rwatch <expr>
+        
+        This command is used to watch a memory location when there is a read
+        operations is performed in it.
+
+-> Breakpoints Part 2 (enable, disable and save breakpoint):
+   +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 
+
+
+   Lets say while analyzing a program under gdb, we have created lot of breakpoints
+   and for the the time being we don't want to stop at each breakpoints we created,
+   but we also don't want to delete it.
+   
+   For that, we can disable the breakpoint.
+
+   Command:
+   (gdb)disable <num>
+        where <num> represent the index of the breakpoint.
+
+   To enable the break point we can use...
+   
+   Command:
+   (gdb)enable <num>
+
+
+   Lets say we are exiting out of the gdb for some reason, but we don't want
+   to again create all the breakpoints and we can save it somewhere it 
+   might be helpful to use it later.
+
+   Command:
+   (gdb)save breakpoints <filename>
+
+    It will save all the breakpoints with it current snapshot and we can use it for
+    latter.
+
+   To load the saved breakpoints later, we can use...
+   
+   Command:
+   (gdb)source <filename>
+
+
+-> Display and undisplay:
+   ++++++++++++++++++++++ 
+
+   * To display the value of certain variable when the execution stop at certain
+     point after the latest command, we can use...
+
+     Command:
+     (gdb) display <expr>
+
+        where <expr> can be variable, address of variable..
+
+   * To see the list of current expression to display.
+
+     Command:
+     (gdb)info display
+
+   * To undisplay the expressions if we want to, we can use...
+
+     Command:
+     (gdb)undisplay <index>
+
+        where <index> correponds to particular expression
+        which is used for display.
+
+   * To display the value of expression under expections.
+
+     Command:
+     (gdb) display /b <expr>
+
+
+-> Getting help in GDB (info):
+   +++++++++++++++++++++++++++ 
+
+   To know about gdb and its command:
+
+   Use: 
+   $man gdb 
+    This is the manual for gdb
+
+
+   To know about gdb commands.
+
+   Command:
+   (gdb)help <command>
+   display the relivant command and information regarding that.
+
+   To know get more detailed information.
+   (gdb)apropos <command>
+
+

gdb.txt

@@ -211,6 +211,12 @@ Command: break <line-number>
 
     These are permanent breakpoint
 
+    Note: To delete a breakpoint we can use
+          command
+
+          Command:
+          (gdb)delete <breakpoint-number>
+
 Command: layout src
 
     To open the TUI with src code.