* Useful dbxrc


set -o path # path searching is enabled and use common unix commands
            # enabled by default.
ignore SIGUSR1
ignore SIGUSR2
dbxenv lookaside on

Commands:
search <string> : search the current file for the string regex.
bsearch <string> : search backwards
dalias : make an alias for a debugging command.
kill : kill only the debugged process.
detach: just detach from the process and allow the process to run further.
dbx - pid : To attach to the process without specifying the exe file.
pathmap  : to specify the source file path
modules -a : list the names of all prog modules
module : print the name of current module
modules -debug : print names of modules with debug info
list <funcname> : To visit a new function when you are at somewhere else.
scope resolution for symbols:
`var  : global variable
`a.c`var :  file static variable or function name
`a.c`func`var : variable in the function
`a.c`func:20`var : variable at file a.c inside function func, line number 20.
                   For block specific variable.
stop in #.mul_func : Prefix # to specify the linker name 
print `foo.c`#staticvar : specify the linker name
whatis var : Tells the type
whereis var : Tells where in all modules the var is found
whatis -t <struct_decl> : prints type info
whatis -e <expr> : prints type info of expression
trace func : whenever this func is called, who called with what args
trace lineno : echo when it is executed
trace expr at lineno :

stop modify &variable : stop when variable is modified
stop variable : same as above with subtle diff, auto alloc of var is a change.
stop if condition;
stop event-spec;

when event-spec { dbx-cmd; [...]}
status, clear, handler -disable, delete, ...
step up; : eqvt to:
when returns { stop; echo returned to $func } cont
or
when in func { stop returns; }

event-spec is one of the following events:
in func, at lineno, at filename:lineno, infunction func (same as in func),
expression (when it becomes true), returns, returns func, step (event when
PC reaches the source line), next, sig <sig>, fault [FLTILL|FLTPE|...],
stop, sync(process has execed. Doesn't work with "stop". Use with "when").
lastrites (process is about to die), dlopen, dlclose, modify addr-expr bytesize,
(used to watch a block of memory being modified),  sysin code|name (sys call
about to be executed), sysout code|name (sys call about to be returned to
usermode) omitting code|name will trace all syscalls. 
Event-spec modifiers could filter the events:
-if cond, if cond, in func,  -count n, -count infinity (stop at 10 -count 100,
 stops only 100th time of reaching the same line. ),
 -temp (temp handler. once stoped gets deleted),
-instr (applies to instruction level), -thread tid, -lwp id

Predefined variables:
$pc, $ins, $lineno, $line, $func, $file, $caller, $proc, $thread, $lwp,
$syscode, $sysname (for use with sysin,sysout events), 

Syntax for call:
call func(par1,par2)
Unconditional Go to line no:
cont at <lineno>
assign <var>=<val>;

#Saving and restoring a debug run:
save file
restore file
up, down, frame, -h +/-number Show hidden frames, go up or down to get the
current scope info for name resolution.

#using examine command
examine &main
examine &addr1,&addr2
examine &addr1/<count><fmt> # e.g. examine &func/10i : 10asm instrs from func
                            # e.g. examine &data/10d : 10dec ints from data
Instead of examine you can also use dis where fmt is understood as "i".

# listi 90,100 displays asm instructions for c source 90 to 100.

To turn on runtime checking (for uninitialized memory access, etc.)
dbx> check -all
or invoke: dbx -C a.out


dbx is ksh compatible for most purposes. Note that backquotes is not 
implemented.

Use -xs (not -Xs) compiler option to put debug info into the executable.




gdb syntax:

break <function>   --- stop in function
info breakpoints   -- show status


- dbx if encountered internal error, changes to /tmp, invokes
  dbx on itself to get the stack trace, then calls abort(); to core
  dump itself. Uses sigaction to capture the signal--> within
  the signal handler immediately set the handler to SIG_DFL, so
  that stack never overflows in case of multiple signal problems
  with in signal handler;

- Use following useful commands:
psig     -- to print all the signals caught by a process
pstack   -- to get the stack trace
pfiles   -- all openfiles
pmap     -- to get process map


Use:
  /usr/ucb/ps -wwagx  ; Complete command however long.
  /usr/ucb/ps -aww ;
  /usr/ucb/ps auxww ; Complete env variables how ever long it is.


gdb 
4.4. Logging output
You may want to save the output of gdb commands to a file. There are several commands to control gdb's logging. 

set logging on
Enable logging. 

set logging off
Disable logging. 

set logging file file
Change the name of the current logfile. The default logfile is gdb.txt. 

set logging overwrite [on|off]
By default, gdb will append to the logfile. Set overwrite if you want set logging on to overwrite the logfile instead. 

set logging redirect [on|off]
By default, gdb output will go to both the terminal and the logfile. Set redirect if you want output to go only to the log file. 

show logging
Show the current values of the logging settings. 

Use: gdb -tui for text user interface.

info win
        SRC     (23 lines)
        CMD     (7 lines)  <has focus>
winheight  SRC  +5
winheight  CMD  -3

until, u
   like step, run till current line changes to next line.
   but this will come out of single line loop.

tty /dev/ttya
   sets controlling terminal for future run commands.

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gdb tracepoint:

   Ideal when like to print without stopping.
   However supported only with gdbserver running:

   You need to set up a remote debugging session (which can still be 
   done on a single machine):

   gdbserver :10000 ./a.out  # start gdbserver listening on port 10000
   In another window:
     gdb -ex 'target remote :10000' ./a.out

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