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     ADB(1)                                                     ADB(1)

          adb - debugger

          adb [-w] [ objfil [ corfil ] ]

          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 mod-
          ified using adb. Adb ignores QUIT; INTERRUPT causes return
          to the next adb command.

          In general requests to adb have 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 value of dot.

          +      The value of dot incremented by the current incre-

          ^      The value of dot decremented by the current incre-

          "      The last address typed.

                 A number.  The prefixes 0o and 0O (zero oh) force
                 interpretation in octal radix; the prefixes 0t and 0T
                 force interpretation in decimal radix; the prefixes
                 0x and 0X or a leading sharp-sign `#' force

     ADB(1)                                                     ADB(1)

                 interpretation in hexadecimal radix.  Thus 0o20 =
                 0t16 = 0x10 = sixteen.  If no prefix appears, then
                 the default radix is used; see the $d command.  The
                 default radix is initially hexadecimal.  The hexadec-
                 imal digits are 0123456789abcdefABCDEF with the obvi-
                 ous values.  Note that a hexadecimal number whose
                 most significant digit would otherwise be an alpha-
                 betic character must have a 0x (or 0X) prefix (or a
                 leading zero if the default radix is hexadecimal).

                 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 reg-
                 ister is obtained from the system header in corfil.
                 The register names are those printed by the $r com-

          symbol A symbol is a sequence of upper or lower case let-
                 ters, underscores or digits, not starting with a
                 digit.   The value of the symbol is taken from the
                 symbol table in objfil. An initial _ or ~ will be
                 prepended to symbol if needed.

          _ symbol
                 In C, the `true name' of an external symbol begins
                 with _.  It may be necessary to utter this name to
                 disinguish it from internal or hidden variables of a

                 The address of the variable name in the specified C
                 routine.  Both routine and name are symbols. If name
                 is omitted the value is the address of the most
                 recently activated C stack frame corresponding to
                 routine; if routine is omitted, the active procedure
                 is assumed.

          (exp)  The value of the expression exp.

          Monadic operators

          *exp   The contents of the location addressed by exp in

          @exp   The contents of the location addressed by exp in

     ADB(1)                                                     ADB(1)


          -exp   Integer negation.

          ~exp   Bitwise complement.'

          %exp   If exp is used as an address, it is in register
                 space; see ADDRESSES .

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

          e2  Integer addition.

          e2  Integer subtraction.

          e2  Integer multiplication.

          e2  Integer division.

          e2  Bitwise conjunction.

          e2  Bitwise disjunction.

          e2  E1 rounded up to the next multiple of e2.

          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 subse-
               quent 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 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.

     ADB(1)                                                     ADB(1)

               o 2  Print 2 bytes in octal.
               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 unsigned decimal.
               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 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 VAX instructions.  n is the number of
                    bytes occupied by the instruction.  This style of
                    printing causes variables 0, (1, ...)  to be set
                    to the offset parts of the first (second, ...)
                    operand of the instruction.
               a 0  Print the value of dot in symbolic form.
               p 4  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
                    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.

               Repeat the previous command 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

     ADB(1)                                                     ADB(1)

               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.

          [?/]m b e f[?/]
               New values for (b, e, f) in the first map entry are
               recorded.  If less than three expressions are given
               then the remaining map parameters are left unchanged.
               The address type (instruction or data) is unchanged in
               any case.  If the `?' or `/' is followed by `*' then
               the second segment 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.)

               Dot is assigned to the variable or register named.

          !    A shell is called to read the rest of the line follow-
               ing `!'.

               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
                    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 stopping
                    or termination, as well as the registers.  This is
                    the default if modifier is omitted.
               r    Print the general registers and the instruction
                    addressed by pc.  Dot is set to pc.
               R    Like $r, but include boring registers like the
                    kernel stack pointer.
               b    Print all breakpoints and their associated counts

     ADB(1)                                                     ADB(1)

                    and commands.
               c    C stack backtrace.  If address is given then it is
                    taken as the address of the current frame (instead
                    of fp).  If C is used then the names and (32 bit)
                    values of all parameters, automatic and static
                    variables are printed for each active function.
                    If count is given then only the first count frames
                    are printed.
               d    Set the default radix to address and report the
                    new value.  Address is interpreted in the (old)
                    current radix; `10$d' never changes the default
                    radix.  To make decimal the default radix, use
                    `0t10$d'.  A radix of zero is a special case:
                    input with a leading zero is octal, that with a
                    leading sharp-sign `#' is hexadecimal, other num-
                    bers are decimal; output is hexadecimal by
                    default; hex and octal numbers are printed with a
                    leading # and 0 respectively.
               e    The names and values of external variables are
               w    Set the page width for output to address (default
               s    Set the limit for symbol matches to address
                    (default 255).
               q    Exit from adb.
               v    Print all non zero variables in the current radix.
               m    Print the address maps.
               k    Simulated VAX memory management: set the system
                    base register pointer to address. System space
                    addresses will hereafter be mapped according to
                    the system page table.  If address is zero, map-
                    ping is turned off.
               p    Set the PCB base pointer to address, which may be
                    either the physical address of a process control
                    block (as found in the PCBB register) or the sys-
                    tem space address of a page table entry which
                    points to a PCB (as found in p_addr). User space
                    addresses will hereafter be translated according
                    to the user page tables pointed to by the PCB.
                    Kernel mapping ($k) must already be in effect.  If
                    address is zero, user mapping is turned off;
                    addresses less than 0x80000000 will be treated as
                    physical addresses.
                    $k and $p are useful for system debugging.

               Manage a subprocess.  Available modifiers are:

               bc   Set breakpoint at address. The breakpoint is exe-
                    cuted 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

     ADB(1)                                                     ADB(1)

                    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.  All signals are
                    turned on on entry to the subprocess.
               cs   The subprocess is continued.  If s is omitted or
                    nonzero, the subprocess is sent the signal that
                    caused it to stop; if 0 is specified, no signal is
                    sent.  Breakpoints and single-stepping don't count
                    as signals.  Breakpoint skipping is the same as
                    for r.
               ss   As for c except that the subprocess is single
                    stepped count times.  If a signal is sent, it is
                    received before the first instruction is executed.
                    If there is no current subprocess 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.

          Adb provides a number of variables.  Named variables are set
          initially by adb but are not used subsequently.  Numbered
          variables are reserved for communication as follows.

          0, 1, ...
               The offset parts of the first, second, ...  operands of
               the last instruction printed.  Meaningless if the
               operand was a register.
          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.
          d    The data segment size.
          e    The entry point.
          m    The `magic' number (0407, 0410 or 0413).
          s    The stack segment size.
          t    The text segment size.

          The address in a file associated with a written address is
          determined by a mapping associated with that file.  Each

     ADB(1)                                                     ADB(1)

          mapping is represented by one or more quadruples (t, b, e,
          f), each mapping addresses of type t (instruction, data,
          user block) in the range b through e to the part of the file
          beginning at address f. An address a of type t is mapped to
          a file address by finding a quadruple of type t, for which
          b≦a<e; the file address is address+f-b.  As a special case,
          if an instruction space address is not found, a second
          search is made for the same address in data space.

          Typically, the text segment of a program is mapped as
          instruction space, the data and bss segments as data space.
          If objfil is an a.out, or if corfil is a core image or pro-
          cess file, maps are set accordingly.  Otherwise, a single
          `data space' map is set up, with b and f set to zero, and e
          set to a huge number; thus the entire file can be examined
          without address translation.

          The ? and / commands attempt to examine instruction and data
          space respectively.  ?* tries for data space (in objfil); /*
          accesses instruction space (in corfil).

          Registers in process and core images are a special case;
          they live in a special `register' address space.  The con-
          tents of register 0 are located at address %0; register 1 at
          %4 (registers are 4 bytes long); and so on.  % addresses are
          mapped to the registers for the `current frame,' set by
          local variable references, and reset to the outermost frame
          (the `real' registers) whenever a process runs or a stack
          trace is requested.

          Simulated memory management translations (the $k and $p com-
          mands) are done before the mapping described above.

          So that adb may be used on large files all appropriate val-
          ues are kept as signed 32 bit integers.

          /usr/lib/adb/*  parameter files

          pi(9.1), sdb(1), proc(4), a.out(5), core(5)

          `Adb' when there is no current command or format.  Comments
          about inaccessible files, syntax errors, abnormal termina-
          tion of commands, etc.  Exit status is 0, unless last com-
          mand failed or returned nonzero status.

          Either the explanation or the implementation of register

     ADB(1)                                                     ADB(1)

          variables is too complex and arcane.

          0$d should probably be the default.