gdb is used to debug the program excutablesgdb requires executable file as inputGDB was first written by Richard Stallman in 1986 as part of his GNU systemtgdb = gnu debuggergdb is terminal based debuggerto have gui(gdb) applications are Nemiver Kdbg DDD, b main Put a breakpoint at the beginning of the programb Put a breakpoint at the current lineb N Put a breakpoint at line Nb +N Put a breakpoint N lines down from the current lineb fn Put a breakpoint at the beginning of function "fn"d N delete breakpoint number Ninfo break list breakpointsr Run the program until a breakpoint or errorc continue running the program until the next breakpoint or errorf Run until the current function is finished (free run function)s run the next line of the programs N run the next N lines of the programn like s, but don't step into functions()u N run until you get N lines in front of the current linep var print the current value of the variable "var"bt print a stack traceup go up a level in the stackdown go down a level in the stackq Quit gdbinfo register = dump all registerr A start with command line argumentdon not step over ndo step in sstep out of function finishl 5 list 10 lines context around line no. 5list 4 same as l 5#to enable reverse-stepb mainrunrecordto stop recor write stop recordto see current line of execution frameto reverse the executeiob by one step reverse-step(i)reverse back to previous statement reverse next(i)reverse back to calling stetment reverse-finish(i)simple blank enter will fire privious command usedexplain1st slide==========|-> what is debugger(keil,turboc)|-> To resolve run time error (segmentation fault and exception)|-> To understand or decode programs logic|-> what is GDB|-> Who developed it?(1986)2nd slide=========|-> how to start with GDB|-> GDB needs compiled or executable file|-> command line GDB demands that both executable must be at same place|-> GUI GDB are Nemiver(c,c++),code-blocks,kDbg, xcode ,DDD etc.|-> GDB allows run time variable change and monitoring variable, register ,memory etc.|-> compile c,c++ file with '-g' flag on => Ex. gcc -g -o 3rd slide=========|-> start with exception file+>./0exeception.out+> gcc -g 0exception.c -o exception.out+> gdb ./0exception.out|-> explain=> gdb ./a.out=> q to quit=> r or run (restart)=> where=> bt (break trace)=> up and down (to change frames)4th slide=========|-> start with 1segment.c file+> gcc -g 1segment.c -o 1segment.out+> gdb ./1segment.out=> Breakpoints+> break (add break poins to next line)+> b n+> b +n +> b name+> info b+> d or d n or delete 3+> clear (will delete the upcomming breakpoint)+> enable or disable breakpoint=> continue or c=> step in+> s+> s n=> step over+> n+> n number=> list lines+> l n or lines n+> l listsize range+> l+> l function_name+> l 1,2 (range)5th slide==========|-> explain 2printf.c file without register +> gcc -g 2.printf.c -o 2printf.out+> gdb ./2printf.out|-> set break points(b mian,21,27,34,39)|-> info register|-> blank enter|-> frame|-> set variable from GDB=>p variable = value|-> watch or del (brakepoint no.)|-> p|-> diplay or undisplay|-> info locals|-> step out+> finish |-> record=> reverse-next (last step)=> reverse-step (last statement)=> reverse-finish (last calling)=> reverse-continue (last breakpoint)|-> untill to step over loop|-> explain with setting register type6th slide=========|-> advantage of GDB => step through code line by line=> exmines register values=> examine memory=> exmine call stacks and frames=> setting up breakpoints=> debugging segmentation fault=> watching variables and setting variables|-> disadvantage of GDB=> memory leak can not be detected|-> show nemiver 7th slide=========|-> valgrind allows memory leak detection|-> it is tool designed specially for memory debgging|-> run memory_leak.c program with gdb=> gcc -g memory_leak.c -o memory_leak.out=> GDB runs program without any error|-> run same program with valgrind=> gcc -g memory_leak.c -o memory_leak.out=> valgrind --leak-check=yes ./memory_leak.outor=> valgrind --tool=memcheck ./memory_leak.out=> ==process-id==|-> runt uninitialzed_variable.c file=> gcc -g uninitialized_variable.c -o uninitialized_variable.out=> valgrind --leak-check=yes ./uninitialized_variable.out|-> ng gdb with valgrindvalgrind --tool=memcheck --leak-check=yes --vgdb=yes --vgdb-error=0 ./uninitialized_variable.out|-> in another shell start program with gdb=>gdb ./uninitialized_variable.out+>(gdb) target remote | vgdb --pid=|-> in combination of valgrind and gdb 'run' command doesn't workbut use continue command to start up|-> this combination will produce memory leackage related error runtime. in the shell in which valgrind error is runing|-> explain massif(memory analysys tool ) with massif_.c program=>gcc -g massif_.c -o massif_.out=>valgrind --tool=massif ./massif_.out=>valgrind --tool=massif --time-unit=B ./massif_.out=> ms_print massif.out.=>valgrind --leak-check=full ./massif_.out|-> try it with freeing memory