1. GDB cheatsheet - page 1
Running <where> next
# gdb <program> [core dump] function_name Go to next instruction (source line) but
Start GDB (with optional core dump). Break/watch the named function. donʻt dive into functions.
# gdb --args <program> <args…> line_number finish
Start GDB and pass arguments Break/watch the line number in the cur- Continue until the current function re-
rent source file. turns.
# gdb --pid <pid>
Start GDB and attach to process. file:line_number continue
Break/watch the line number in the Continue normal execution.
set args <args...>
named source file.
Set arguments to pass to program to Variables and memory
be debugged. Conditions print/format <what>
break/watch <where> if <condition> Print content of variable/memory locati-
run
Break/watch at the given location if the on/register.
Run the program to be debugged.
condition is met. display/format <what>
kill Conditions may be almost any C ex- Like „print“, but print the information
Kill the running program. pression that evaluate to true or false. after each stepping instruction.
Breakpoints condition <breakpoint#> <condition> undisplay <display#>
break <where> Set/change the condition of an existing Remove the „display“ with the given
Set a new breakpoint. break- or watchpoint. number.
delete <breakpoint#> Examining the stack enable display <display#>
Remove a breakpoint. backtrace disable display <display#>
clear where En- or disable the „display“ with the gi-
Delete all breakpoints. Show call stack. ven number.
enable <breakpoint#> backtrace full x/nfu <address>
Enable a disabled breakpoint. where full Print memory.
Show call stack, also print the local va- n: How many units to print (default 1).
disable <breakpoint#> f: Format character (like „print“).
riables in each frame.
Disable a breakpoint. u: Unit.
frame <frame#>
Watchpoints Select the stack frame to operate on. Unit is one of:
watch <where>
b: Byte,
Set a new watchpoint. Stepping
h: Half-word (two bytes)
step
delete/enable/disable <watchpoint#>
w: Word (four bytes)
Go to next instruction (source line), di-
Like breakpoints.
g: Giant word (eight bytes)).
ving into function.
© 2007 Marc Haisenko <marc@darkdust.net>

2. GDB cheatsheet - page 2
Format Manipulating the program Informations
a
Pointer. set var <variable_name>=<value> disassemble
c
Read as integer, print as character. Change the content of a variable to the disassemble <where>
d
Integer, signed decimal. given value. Disassemble the current function or
f
Floating point number. given location.
return <expression>
o
Integer, print as octal. Force the current function to return im- info args
s
Try to treat as C string. mediately, passing the given value. Print the arguments to the function of
t
Integer, print as binary (t = „two“). the current stack frame.
u
Integer, unsigned decimal. Sources
x
Integer, print as hexadecimal. directory <directory> info breakpoints
Print informations about the break- and
<what> Add directory to the list of directories
that is searched for sources. watchpoints.
expression
Almost any C expression, including list info display
function calls (must be prefixed with a list <filename>:<function> Print informations about the „displays“.
cast to tell GDB the return value type). list <filename>:<line_number> info locals
file_name::variable_name list <first>,<last> Print the local variables in the currently
Content of the variable defined in the Shows the current or given source con- selected stack frame.
named file (static variables). text. The filename may be omitted. If
last is omitted the context starting at info sharedlibrary
function::variable_name start is printed instead of centered a- List loaded shared libraries.
Content of the variable defined in the round it. info signals
named function (if on the stack). List all signals and how they are cur-
set listsize <count>
{type}address Set how many lines to show in „list“. rently handled.
Content at address, interpreted as info threads
being of the C type type. Signals List all threads.
$register handle <signal> <options>
Set how to handle signles. Options are: show directories
Content of named register. Interesting Print all directories in which GDB sear-
registers are $esp (stack pointer), $ebp (no)print: (Donʻt) print a message when ches for source files.
(frame pointer) and $eip (instruction signals occurs.
pointer). show listsize
(no)stop: (Donʻt) stop the program Print how many are shown in the „list“
Threads when signals occurs. command.
thread <thread#> (no)pass: (Donʻt) pass the signal to the whatis variable_name
Chose thread to operate on. program. Print type of named variable.
© 2007 Marc Haisenko <marc@darkdust.net>