1. Executables have to be first compiled with -g flag so that extra information such as source code & line number are embedded into the executables

2. To execute gdb: gdb <EXECUTABLE_NAME>
   • To debug an executable which requires cmdline arguments: gdb --args <EXECUTABLE_NAME> <ARGUMENTS> or specify args within gdb
3. Flow control commands (square brackets can be abbreviated):
   • r[un]: Run the executable
     • To specify args for execution: r <ARGS>
   • b[reak] <TARGET>: Create a breakpoint at location <TARGET> where <TARGET> can be one of the following:
     • function_name
       • Supports class name, scope resolution operator
       • In case of overloaded function, can uniquely identify by providing parameter types
       • If fully namespace-qualified, a <TAB> would prompt gdb to do tab-completion
     • file_name:function_name
     • line_number
     • file_name:line_number
     • +offset, -offset: position from currently selected stack frame
     • No argument: break at next instruction in the currently selected stack frame
   • rbreak <TARGET>: To enable wildcards and regex in breakpoint matching
   • s[tep]: Continue to the next instruction
   • n[ext]: Continue to the next stack frame (after completing the current stack frame)
   • c[ontinue]: Continue to the next breakpoint or the end of the program
   • d[el[ete]] <BREAKPOINT_ID>: Deletes the breakpoint with ID <BREAKPOINT_ID>
     • Run w/o any argument to delete all breakpoints at once
   • disable <BREAKPOINT_ID>: Disables the breakpoint with ID <BREAKPOINT_ID>
     • Run w/o any argument to disable all breakpoints at once
   • q[uit]: Quits gdb
     • Can be called during run
4. Observation commands
   • info <ITEM>: Shows a list of <ITEM> which can be one of the following:
     • b[reakpoints]: List all breakpoints (ID, line info, etc.)
     • sharedlibrary: List all dynamically-linked libraries as of now
     • f[rame]: Describes the current stack frame
     • r[egisters]: List of registers and the values they are currently storing
   • p[rint] <VARIABLE>: Prints the value of <VARIABLE>
     • Many variants here; TODO: fill in
     • Use ptype instead to print a type (works for recent enough gdb)
   • f[rame]: Shows the current frame as well as instruction as a line in the source code
   • l[ist]: Shows the current source code line + a few lines above & below
     • Continuously running list prints out the subsequent lines until the end of the current source file
   • b[ack]t[race]: Shows the stack trace to the current stack frame
     • where is an exact synonym
   • disas <FUNCTION_NAME>: Disassemble <FUNCTION_NAME> to see the underlying assembly code
5. gdb & templates
   • Templates can be used to uniquely specify breakpoints
     • e.g. b Foo<const char *>::Foo
   • To break on all instances of class template Foo: rbreak Foo<.*>
6. Misc.
   • Meaning of <FUNCTION_NAME>@plt: refer to reference (*)
   • "No symbol XXX in current context": Variable may have been optimized out during compilation; remove any optimization by specifying -O0 flag to compiler

References:

• https://ftp.gnu.org/old-gnu/Manuals/gdb/html_node/gdb_28.html
• https://stackoverflow.com/questions/6121094/how-do-i-run-a-program-with-commandline-arguments-using-gdb-within-a-bash-script
• https://stackoverflow.com/questions/59599200/clear-all-breakpoints-in-gdb
• https://stackoverflow.com/questions/39421971/in-gdb-whats-the-difference-between-where-bt-and-i-frame-commands
• https://stackoverflow.com/questions/14581837/gdb-how-to-print-the-current-line-or-find-the-current-line-number
• https://cets.seas.upenn.edu/answers/gcc.html
• https://stackoverflow.com/questions/35806129/c-gdb-breakpoint-for-member-functions
• https://stackoverflow.com/questions/33661179/debug-c-template-with-gdb?rq=1
• https://stackoverflow.com/questions/5469274/what-does-plt-mean-here (*)
• https://stackoverflow.com/questions/3758614/gdb-no-symbol-i-in-current-context
• Reference for examining source files