Videos

• gdbtui and C code
• gdbtui and Assembly code

Setup

To have the compiler or assembler output an object file with debugging information, add -g to the command line when compiling or assembling:

gcc -g ... somecode.c
as -g ... somecode.S

Then you can start gdbtui with your executable program:

gdbtui ./program

Generally Relevant

• run: start the execution of the program.
• break 123: set a breakpoint at line 123 of the source. i.e. if execution hits that line, pause before starting that line of code.
• next: execute to the next line of code, moving into any function called.
• step: execute to the next line of code, skipping execution of any function called.
• cont: continue execution (until the next breakpoint/watchpoint or the end of the program).

Some non-command keypresses:

• arrows: move around the source code in the upper pane.
• enter: repeat the last step or next command, moving another line.
• ctrl-P: scroll up to previous commands.
• ctrl-L: redraw the screen.

Relevant to C Code

• print x: print the current contents of the variable x.
• watch x: "watch" the variable x. i.e. whenever x changes, pause execution and display the old/new value.
• backtrace: display the current callback stack.
• finish: execute until the current function returns (then pause).

Relevant to Assembly

• break foo: set a breakpoint at a label in the source file.
• print (int)x: print the current contents of the memory location x, treating it as the given type.
• print $rdi: print a register value. (Note: it's a $ not a %.)
• watch $rdi: watch a register value. (Note: it's a $ not a %.)
• info registers rax: print register contents
• info registers eflags: print status flags