# 2.11BSD#431 - /usr/man/cat1/adb.0

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

    NAME
         adb - debugger (2BSD)

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

    DESCRIPTION
         Adb 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.

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

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

         The -k option makes adb do UNIX kernel memory mapping; it
         should be used when core is a UNIX crash dump or /dev/mem.

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

         Adb ignores QUIT; INTERRUPT causes return to the next adb
         command.

         In general requests to adb are of the form

    		[address]  [, count] [command] [;]

         If address is present then dot is set to address.	Initially
         dot is set to 0.  For most commands count specifies how many
         times the command will be executed.  The default count is 1.
         Address and count 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 dot.

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

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

         "	    The last address typed.

         integer
    	    An octal number if integer 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.

         integer.fraction
    	    A 32 bit floating point number.

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

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

         symbol A symbol 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 symbol is
    	    taken from the symbol table in objfil.  An initial _
    	    or ~ will be prepended to symbol if needed.  If the
    	    symbol is a text symbol and objfil is an overlay
    	    type, the default is ~symbol, which is the subroutine
    	    itself, not the entry interface in the base segment.

         _ symbol
    	    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, ~symbol is
    	    the actual subroutine, and _symbol 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: \~symbol must be typed.

         routine.name
    	    The address of the variable name in the specified C
    	    routine.  Both routine and name are symbols.  If name

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

         (exp)  The value of the expression exp.

         Monadic operators

         *exp   The contents of the location addressed by exp in cor-
    	    fil.

         @exp   The contents of the location addressed by exp in
    	    objfil.

         -exp   Integer negation.

         ~exp   Bitwise complement.

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

         e1+e2  Integer addition.

         e1-e2  Integer subtraction.

         e1*e2  Integer multiplication.

         e1%e2  Integer division.

         e1&e2  Bitwise conjunction.

         e1|e2  Bitwise disjunction.

         e1#e2  E1 rounded up to the next multiple of e2.

    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 address in objfil are printed
    	  according to the format f.  dot is incremented by the
    	  sum of the increments for each format letter (q.v.).

         /f   Locations starting at address in corfil are printed
    	  according to the format f and dot is incremented as for
    	  `?'.

         =f   The value of address 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 format 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 dot 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 adb 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 ctime(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 dot 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.
    	  ^    Dot is decremented by the current increment.
    	       Nothing is printed.
    	  +    Dot is incremented by 1.  Nothing is printed.
    	  -    Dot is decremented by 1.  Nothing is printed.

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

         [?/]l value mask
    	  Words starting at dot are masked with mask and compared
    	  with value 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 dot is unchanged; otherwise dot is
    	  set to the matched location.	If mask is omitted then
    	  -1 is used.

         [?/]w value ...
    	  Write the 2-byte value 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 b1 e1 f1[?/]
    	  New values for (b1, e1, f1) 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 (b2,e2,f2) of the
    	  mapping is changed.  If the list is terminated by `?'
    	  or `/' then the file (objfil or corfil respectively) is
    	  used for subsequent requests.  (So that, for example,
    	  `/m?' will cause `/' to refer to objfil.)

         >name
    	  Dot is assigned to the variable or register named.

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

         $modifier
    	  Miscellaneous commands.  The available modifiers 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 count 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 modifier is omitted.
    	  r    Print the general registers and the instruction
    	       addressed by pc.  Dot 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 address is given
    	       then it is taken to be the address of the current
    	       frame (instead of r4).  If count is given then
    	       only the first count frames are printed.
    	  c    C stack backtrace.  If address 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 count is given then only
    	       the first count frames are printed.
    	  e    The names and values of external variables are
    	       printed.
    	  w    Set the page width for output to address (default
    	       80).
    	  s    Set the limit for symbol matches to address
    	       (default 255).
    	  o    All integers input are regarded as octal.
    	  d    Reset integer input as described in EXPRESSIONS.
    	  q    Exit from adb.
    	  v    Print all non zero variables in octal.
    	  m    Print the address map.

         :modifier
    	  Manage a subprocess.	Available modifiers are:

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

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

    	  d    Delete breakpoint at address.

    	  r    Run objfil as a subprocess.  If address is given
    	       explicitly then the program is entered at this
    	       point; otherwise the program is entered at its
    	       standard entry point.  count 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.

    	  cs   The subprocess is continued with signal s, see
    	       sigvec(2).  If address 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.

    	  ss   As for c except that the subprocess is single
    	       stepped count times.  If there is no current sub-
    	       process then objfil 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
         Adb provides a number of variables.  Named variables are set
         initially by adb 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
         corfil.  If corfil does not appear to be a core file then
         these values are set from objfil.

         b	  The base address of the data segment.
         c	  The current overlay.	This is set from corfil, 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 (b1, e1, f1),
         (bo, eo, fo) for overlaid object files, and (b2, e2, f2) and
         the file address corresponding to a written address is cal-
         culated as follows.

    	b1<address<e1 => file address=address+f1-b1, otherwise,

         if overlaid,
    	bo<address<eo => file address=address+fo-bo, otherwise,

    	b2<address<e2 => file address=address+f2-b2,

         otherwise, the requested address 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, b1 is set to 0, e1 is set to
         the maximum file size and f1 is set to 0; in this way the
         whole file can be examined with no address translation.

         So that adb 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)
         ADB - A Tutorial, 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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