Summary of GDB commands for x86 Systems

  Command                  Effect


Starting and stopping

  quit                      Exit gdb
  run                       Run your program
  run <command line args>   Run your program using the specific command-line arguments


Breakpoints

  break sum                 Set breakpoint at the entry to function sum
  break *0x80483c3          Set breakpoint at address 0x80483c3
  delete 1                  Delete breakpoint 1 (gdb numbers each breakpoint you create)
  delete                    Delete all breakpoints
  until 3                   Continue executing until the program hits breakpoint 3

Execution

  stepi                     Execute one instruction
  stepi 4                   Execute four instructions
  nexti                     Like stepi, but proceed proceed through function calls without stopping
  continue                  Resume execution until the next breakpoint
  finish                    Resume execution until current function returns


Examining code

  disas                     Disassemble current function
  disas sum                 Disassemble function sum
  disas 0x80483b7           Disassemble function around 0x80483b7
  disas 0x80483b7 0x80483c7 Disassemble code within specified address range

  print /x $eip             Print program counter in hex
  print /d $eip             Print program counter in decimal
  print /t $eip             Print program counter in binary

  call sum(1, 2)            Call sum(1,2) and print return value


Examining data

  print /d $eax             Print contents of %eax in decimal
  print /x $eax             Print contents of %eax in hex
  print /t $eax             Print contents of %eax in binary			    
  print 0x100               Print decimal representation of 0x100
  print /x 555              Print hex representation of 555
  print /x ($esp+8)         Print (contents of %esp) + 8 in hex
  print *(int *) 0xbffff890 Print integer at address 0xbffff890
  print *(int *) ($esp+8)   Print integer at address %esp + 8
  print (char *) 0xbfff890  Examine a string stored at 0xbffff890

  x/w   0xbffff890          Examine (4-byte) word starting at address 0xbffff890
  x/w   $esp                Examine (4-byte) word starting at address in $esp
  x/wd  $esp                Examine (4-byte) word starting at address in $esp. Print in decimal
  x/a   $esp                Examine address in $esp. Print as offset from previous global symbol.
  
  x/s   0xbffff890          Examine a string stored at 0xbffff890

  x/20b sum                 Examine first 20 opcode bytes of function sum
  x/10i sum                 Examine first 10 instructions of function sum

  (Note: the format string for the `x' command has the general form 
     x/[NUM][SIZE][FORMAT] where
 
    NUM  = number of objects to display
    SIZE = size of each object (b=byte, h=half-word, w=word, g=giant (quad-word))
    FORMAT = how to display each object (d=decimal, x=hex, o=octal, etc.)

    If you don't specify SIZE or FORMAT, either a default value, or the last
    value you specified in a previous `print' or `x' command is used.
  )

Useful information

  info frame                Print available information about current stack frame
  info registers            Print values in all registers
  display /FMT EXPR         Print expression EXPR using format FMT ever time GDB stops
  undisplay                 Turn off display mode
  help                      Get information about gdb