


ADB(1)		    UNIX Programmer's Manual		   ADB(1)



NAME
     adb - debugger (2BSD)

SYNOPSIS
     adb [-w] [ -k ] [ -Idir ] [ objfil [ corfil ] ]

DESCRIPTION
     _A_d_b is a general purpose debugging program.  It may be used
     to examine files and to provide a controlled environment for
     the execution of UNIX programs.

     _O_b_j_f_i_l is normally an executable program file, preferably
     containing a symbol table; if not then the symbolic features
     of _a_d_b cannot be used although the file can still be exam-
     ined.  The default for _o_b_j_f_i_l is a.out. _C_o_r_f_i_l is assumed to
     be a core image file produced after executing _o_b_j_f_i_l; the
     default for _c_o_r_f_i_l is core.

     Requests to _a_d_b are read from the standard input and
     responses are to the standard output.  If the -w flag is
     present then both _o_b_j_f_i_l and _c_o_r_f_i_l are created if necessary
     and opened for reading and writing so that files can be
     modified using _a_d_b.

     The -k option makes _a_d_b do UNIX kernel memory mapping; it
     should be used when _c_o_r_e is a UNIX crash dump or /_d_e_v/_m_e_m.

     The -I option specifies a directory where files to be read
     with $< or $<< (see below) will be sought; the default is
     /_u_s_r/_s_h_a_r_e/_a_d_b.

     _A_d_b ignores QUIT; INTERRUPT causes return to the next _a_d_b
     command.

     In general requests to _a_d_b are of the form

		[_a_d_d_r_e_s_s]  [, _c_o_u_n_t] [_c_o_m_m_a_n_d] [;]

     If _a_d_d_r_e_s_s is present then _d_o_t is set to _a_d_d_r_e_s_s.	Initially
     _d_o_t is set to 0.  For most commands _c_o_u_n_t specifies how many
     times the command will be executed.  The default _c_o_u_n_t is 1.
     _A_d_d_r_e_s_s and _c_o_u_n_t are expressions.

     The interpretation of an address depends on the context it
     is used in.  If a subprocess is being debugged then
     addresses are interpreted in the usual way in the address
     space of the subprocess.  For further details of address
     mapping see ADDRESSES.

EXPRESSIONS
     .	    The value of _d_o_t.




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     +	    The value of _d_o_t incremented by the current incre-
	    ment.

     ^	    The value of _d_o_t decremented by the current incre-
	    ment.

     "	    The last _a_d_d_r_e_s_s typed.

     _i_n_t_e_g_e_r
	    An octal number if _i_n_t_e_g_e_r begins with a 0; a hexade-
	    cimal number if preceded by #; otherwise a decimal
	    number.  This default interpretation of integers may
	    be changed via the $o and $d commands.

     _i_n_t_e_g_e_r._f_r_a_c_t_i_o_n
	    A 32 bit floating point number.

     '_c_c_c_c' The ASCII value of up to 4 characters.  \ may be used
	    to escape a '.

     < _n_a_m_e The value of _n_a_m_e, which is either a variable name or
	    a register name.  _A_d_b maintains a number of variables
	    (see VARIABLES) named by single letters or digits.
	    If _n_a_m_e is a register name then the value of the
	    register is obtained from the system header in _c_o_r_-
	    _f_i_l.  The register names are those printed by the $r
	    command.

     _s_y_m_b_o_l A _s_y_m_b_o_l is a sequence of upper or lower case
	    letters, underscores or digits, not starting with a
	    digit.  The backslash character \ may be used to
	    escape other characters.  The value of the _s_y_m_b_o_l is
	    taken from the symbol table in _o_b_j_f_i_l.  An initial _
	    or ~ will be prepended to _s_y_m_b_o_l if needed.  If the
	    symbol is a text symbol and _o_b_j_f_i_l is an overlay
	    type, the default is ~_s_y_m_b_o_l, which is the subroutine
	    itself, not the entry interface in the base segment.

     _ _s_y_m_b_o_l
	    In C, the `true name' of an external symbol begins
	    with _.  It may be necessary to utter this name to
	    distinguish it from internal or hidden variables of a
	    program.  For a subroutine in an overlay, ~_s_y_m_b_o_l is
	    the actual subroutine, and __s_y_m_b_o_l is the entry point
	    in the base segment (the "thunk").	Note that to
	    explicitly specify the local name, the ~ must be pre-
	    ceeded by a backslash, since ~ is the bitwise comple-
	    ment operator: _\~_s_y_m_b_o_l must be typed.

     _r_o_u_t_i_n_e._n_a_m_e
	    The address of the variable _n_a_m_e in the specified C
	    routine.  Both _r_o_u_t_i_n_e and _n_a_m_e are _s_y_m_b_o_l_s.  If _n_a_m_e



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	    is omitted the value is the address of the most
	    recently activated C stack frame corresponding to
	    _r_o_u_t_i_n_e.

     (_e_x_p)  The value of the expression _e_x_p.

     Monadic operators

     *_e_x_p   The contents of the location addressed by _e_x_p in _c_o_r_-
	    _f_i_l.

     @_e_x_p   The contents of the location addressed by _e_x_p in
	    _o_b_j_f_i_l.

     -_e_x_p   Integer negation.

     ~_e_x_p   Bitwise complement.

     Dyadic operators are left associative and are less binding
     than monadic operators.

     _e_1+_e_2  Integer addition.

     _e_1-_e_2  Integer subtraction.

     _e_1*_e_2  Integer multiplication.

     _e_1%_e_2  Integer division.

     _e_1&_e_2  Bitwise conjunction.

     _e_1|_e_2  Bitwise disjunction.

     _e_1#_e_2  _E_1 rounded up to the next multiple of _e_2.

COMMANDS
     Most commands consist of a verb followed by a modifier or
     list of modifiers.  The following verbs are available.  (The
     commands `?' and `/' may be followed by `*'; see ADDRESSES
     for further details.)

     ?_f   Locations starting at _a_d_d_r_e_s_s in _o_b_j_f_i_l are printed
	  according to the format _f.  _d_o_t is incremented by the
	  sum of the increments for each format letter (q.v.).

     /_f   Locations starting at _a_d_d_r_e_s_s in _c_o_r_f_i_l are printed
	  according to the format _f and _d_o_t is incremented as for
	  `?'.

     =_f   The value of _a_d_d_r_e_s_s itself is printed in the styles
	  indicated by the format _f.  (For i format `?' is
	  printed for the parts of the instruction that reference



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	  subsequent words.)

     A _f_o_r_m_a_t consists of one or more characters that specify a
     style of printing.  Each format character may be preceded by
     a decimal integer that is a repeat count for the format
     character.  While stepping through a format _d_o_t is incre-
     mented temporarily by the amount given for each format
     letter.  If no format is given then the last format is used.
     The format letters available are as follows.

	  o 2  Print 2 bytes in octal.	All octal numbers output
	       by _a_d_b are preceded by 0.
	  O 4  Print 4 bytes in octal.
	  q 2  Print in signed octal.
	  Q 4  Print long signed octal.
	  d 2  Print in decimal.
	  D 4  Print long decimal.
	  x 2  Print 2 bytes in hexadecimal.
	  X 4  Print 4 bytes in hexadecimal.
	  u 2  Print as an unsigned decimal number.
	  U 4  Print long unsigned decimal.
	  f 4  Print the 32 bit value as a floating point number.
	  F 8  Print double floating point.
	  b 1  Print the addressed byte in octal.
	  c 1  Print the addressed character.
	  C 1  Print the addressed character using the following
	       escape convention.  the standard escape convention
	       where control characters are printed as ^X and the
	       delete character is printed as ^?.
	  s _n  Print the addressed characters until a zero char-
	       acter is reached.
	  S _n  Print a string using the ^_X escape convention (see
	       C above).  _n is the length of the string including
	       its zero terminator.
	  Y 4  Print 4 bytes in date format (see _c_t_i_m_e(3)).
	  i n  Print as machine instructions.  _n is the number of
	       bytes occupied by the instruction.  This style of
	       printing causes variables 1 and 2 to be set to the
	       offset parts of the source and destination respec-
	       tively.
	  a 0  Print the value of _d_o_t in symbolic form.  Symbols
	       are checked to ensure that they have an appropri-
	       ate type as indicated below.

	    /  local or global data symbol
	    ?  local or global text symbol
	    =  local or global absolute symbol

	  p 2  Print the addressed value in symbolic form using
	       the same rules for symbol lookup as a.
	  t 0  When preceded by an integer tabs to the next
	       appropriate tab stop.  For example, 8t moves to



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	       the next 8-space tab stop.
	  r 0  Print a space.
	  n 0  Print a newline.
	  "..." 0
	       Print the enclosed string.
	  ^    _D_o_t is decremented by the current increment.
	       Nothing is printed.
	  +    _D_o_t is incremented by 1.  Nothing is printed.
	  -    _D_o_t is decremented by 1.  Nothing is printed.

     newline
	  If the previous command temporarily incremented _d_o_t,
	  make the increment permanent.  Repeat the previous com-
	  mand with a _c_o_u_n_t of 1.

     [?/]l _v_a_l_u_e _m_a_s_k
	  Words starting at _d_o_t are masked with _m_a_s_k and compared
	  with _v_a_l_u_e until a match is found.  If L is used then
	  the match is for 4 bytes at a time instead of 2.  If no
	  match is found then _d_o_t is unchanged; otherwise _d_o_t is
	  set to the matched location.	If _m_a_s_k is omitted then
	  -1 is used.

     [?/]w _v_a_l_u_e ...
	  Write the 2-byte _v_a_l_u_e into the addressed location.  If
	  the command is W, write 4 bytes.  Odd addresses are not
	  allowed when writing to the subprocess address space.

     [?/]m _b_1 _e_1 _f_1[?/]
	  New values for (_b_1, _e_1, _f_1) are recorded.  If less than
	  three expressions are given then the remaining map
	  parameters are left unchanged.  If the `?' or `/' is
	  followed by `*' then the last segment (_b_2,_e_2,_f_2) of the
	  mapping is changed.  If the list is terminated by `?'
	  or `/' then the file (_o_b_j_f_i_l or _c_o_r_f_i_l respectively) is
	  used for subsequent requests.  (So that, for example,
	  `/m?' will cause `/' to refer to _o_b_j_f_i_l.)

     >_n_a_m_e
	  _D_o_t is assigned to the variable or register named.

     !	  A shell (/bin/sh) is called to read the rest of the
	  line following `!'.

     $_m_o_d_i_f_i_e_r
	  Miscellaneous commands.  The available _m_o_d_i_f_i_e_r_s are:

	  <_f   Read commands from the file _f.  If this command is
	       executed in a file, further commands in the file
	       are not seen.  If _f is omitted, the current input
	       stream is terminated.  If a _c_o_u_n_t is given, and is
	       zero, the command will be ignored.  The value of



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	       the count will be placed in variable _9 before the
	       first command in _f is executed.
	  <<_f  Similar to < except it can be used in a file of
	       commands without causing the file to be closed.
	       Variable _9 is saved during the execution of this
	       command, and restored when it completes.  There is
	       a (small) finite limit to the number of << files
	       that can be open at once.
	  >_f   Append output to the file _f, which is created if
	       it does not exist.  If _f is omitted, output is
	       returned to the terminal.
	  ?    Print process id, the signal which caused stoppage
	       or termination, as well as the registers as $r.
	       This is the default if _m_o_d_i_f_i_e_r is omitted.
	  r    Print the general registers and the instruction
	       addressed by pc.  _D_o_t is set to pc.
	  f    Print the floating registers in single or double
	       length.	If the floating point status of ps is set
	       to double (0200 bit) then double length is used
	       anyway.
	  b    Print all breakpoints and their associated counts
	       and commands.
	  a    ALGOL 68 stack backtrace.  If _a_d_d_r_e_s_s is given
	       then it is taken to be the address of the current
	       frame (instead of r4).  If _c_o_u_n_t is given then
	       only the first _c_o_u_n_t frames are printed.
	  c    C stack backtrace.  If _a_d_d_r_e_s_s is given then it is
	       taken as the address of the current frame instead
	       of the contents of the frame-pointer register.  If
	       C is used then the names and (16 bit) values of
	       all automatic and static variables are printed for
	       each active function.  If _c_o_u_n_t is given then only
	       the first _c_o_u_n_t frames are printed.
	  e    The names and values of external variables are
	       printed.
	  w    Set the page width for output to _a_d_d_r_e_s_s (default
	       80).
	  s    Set the limit for symbol matches to _a_d_d_r_e_s_s
	       (default 255).
	  o    All integers input are regarded as octal.
	  d    Reset integer input as described in EXPRESSIONS.
	  q    Exit from _a_d_b.
	  v    Print all non zero variables in octal.
	  m    Print the address map.

     :_m_o_d_i_f_i_e_r
	  Manage a subprocess.	Available modifiers are:

	  b_c   Set breakpoint at _a_d_d_r_e_s_s.  If _o_b_j_f_i_l is overlaid
	       and _a_d_d_r_e_s_s is in the overlay region, the break-
	       point is set in the overlay of the symbol men-
	       tioned if _a_d_d_r_e_s_s was given symbolically,



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	       otherwise it is set in the current overlay (that
	       in variable c).	The breakpoint is executed
	       _c_o_u_n_t-1 times before causing a stop.  Each time
	       the breakpoint is encountered the command _c is
	       executed.  If this command is omitted or sets _d_o_t
	       to zero then the breakpoint causes a stop.

	  d    Delete breakpoint at _a_d_d_r_e_s_s.

	  r    Run _o_b_j_f_i_l as a subprocess.  If _a_d_d_r_e_s_s is given
	       explicitly then the program is entered at this
	       point; otherwise the program is entered at its
	       standard entry point.  _c_o_u_n_t specifies how many
	       breakpoints are to be ignored before stopping.
	       Arguments to the subprocess may be supplied on the
	       same line as the command.  An argument starting
	       with < or > causes the standard input or output to
	       be established for the command.

	  c_s   The subprocess is continued with signal _s, see
	       _s_i_g_v_e_c(2).  If _a_d_d_r_e_s_s is given then the subpro-
	       cess is continued at this address.  If no signal
	       is specified then the signal that caused the sub-
	       process to stop is sent.  Breakpoint skipping is
	       the same as for r.

	  s_s   As for c except that the subprocess is single
	       stepped _c_o_u_n_t times.  If there is no current sub-
	       process then _o_b_j_f_i_l is run as a subprocess as for
	       r.  In this case no signal can be sent; the
	       remainder of the line is treated as arguments to
	       the subprocess.

	  k    The current subprocess, if any, is terminated.

VARIABLES
     _A_d_b provides a number of variables.  Named variables are set
     initially by _a_d_b but are not used subsequently (except for
     c).  Numbered variables are reserved for communication as
     follows.

     0	  The last value printed.
     1	  The last offset part of an instruction source.
     2	  The previous value of variable 1.
     9	  The count on the last $< or $<< command.

     On entry the following are set from the system header in the
     _c_o_r_f_i_l.  If _c_o_r_f_i_l does not appear to be a core file then
     these values are set from _o_b_j_f_i_l.

     b	  The base address of the data segment.
     c	  The current overlay.	This is set from _c_o_r_f_i_l, and in



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	  turn sets the overlay map.  This variable and the map
	  may be changed by referring to other overlays symboli-
	  cally (e.g. by examining text in subroutines in other
	  overlays), using the $r command (which resets c from
	  the core file), or explicitly (with the command >c).
     d	  The data segment size.
     e	  The entry point.
     m	  The `magic' number (0405, 0407, 0410, 0411, 0430 or
	  0431).  The object is overlaid if m is 0430 or 0431.
     o	  The sum of the overlay segment sizes (if overlaid).
     s	  The stack segment size.
     t	  The text segment size.

ADDRESSES
     The address in a file associated with a written address is
     determined by a mapping associated with that file.  Each
     mapping is represented by two or three triples (_b_1, _e_1, _f_1),
     (_b_o, _e_o, _f_o) for overlaid object files, and (_b_2, _e_2, _f_2) and
     the _f_i_l_e _a_d_d_r_e_s_s corresponding to a written _a_d_d_r_e_s_s is cal-
     culated as follows.

	_b_1<__a_d_d_r_e_s_s<_e_1 => _f_i_l_e _a_d_d_r_e_s_s=_a_d_d_r_e_s_s+_f_1-_b_1, otherwise,

     if overlaid,
	_b_o<__a_d_d_r_e_s_s<_e_o => _f_i_l_e _a_d_d_r_e_s_s=_a_d_d_r_e_s_s+_f_o-_b_o, otherwise,

	_b_2<__a_d_d_r_e_s_s<_e_2 => _f_i_l_e _a_d_d_r_e_s_s=_a_d_d_r_e_s_s+_f_2-_b_2,

     otherwise, the requested _a_d_d_r_e_s_s is not legal.  In some
     cases (e.g. for programs with separated I and D space) the
     two segments for a file may overlap.  If a ? or / is fol-
     lowed by an * then only the last triple is used.

     The initial setting of both mappings is suitable for normal
     a.out and core files.  If the object file is not of the kind
     expected then, for both files, _b_1 is set to 0, _e_1 is set to
     the maximum file size and _f_1 is set to 0; in this way the
     whole file can be examined with no address translation.

     So that _a_d_b may be used on large files all appropriate
     values are kept as signed 32 bit integers.

FILES
     a.out
     core

SEE ALSO
     cc(1), ptrace(2), a.out(5), core(5)
     _A_D_B - _A _T_u_t_o_r_i_a_l, S. R. Bourne

DIAGNOSTICS
     `Adb' when there is no current command or format.	Comments



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     about inaccessible files, syntax errors, abnormal termina-
     tion of commands, etc.  Exit status is 0, unless last com-
     mand failed or returned nonzero status.

BUGS
     When single stepping, system calls do not count as an exe-
     cuted instruction.
     Local variables whose names are the same as an external
     variable may foul up the accessing of the external.
     Local variables cannot be accessed in routines that are in
     overlays.
     Since no shell is invoked to interpret the arguments of the
     :r command, the customary wild-card and variable expansions
     cannot occur.









































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