ADB(1)                                                     ADB(1)

     NAME
          adb - debugger

     SYNOPSIS
          adb [-w] [ 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 mod-
          ified using 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.

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

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

          "      The last address typed.

     ADB(1)                                                     ADB(1)

          integer
                 An octal number if integer begins with a 0; a hex-
                 adecimal number if preceded by #; otherwise a decimal
                 number.

          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 reg-
                 ister is obtained from the system header in corfil.
                 The register names are r0 ... r5 sp pc ps.

          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
                 program.

          routine.name
                 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.

          (exp)  The value of the expression exp.

          Monadic operators

          *exp   The contents of the location addressed by exp in
                 corfil.

          @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

     ADB(1)                                                     ADB(1)

          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.

     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.

          /f   Locations starting at address in corfil are printed
               according to the format f.

          =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 temporarily by the amount given for each format let-
          ter.  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.

     ADB(1)                                                     ADB(1)

               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.  Character values 000 to 040
                    are printed as @ followed by the corresponding
                    character in the range 0100 to 0140.  The charac-
                    ter @ is printed as @@.
               s n  Print the addressed characters until a zero char-
                    acter is reached.
               S n  Print a string using the @ escape convention.  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 PDP11 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
                    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

     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.  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 second segment (b2,e2,f2) of
               the mapping is changed.  If the list is terminated by
               `?' or `/' then the file (objfil or corfil respec-
               tively) 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 is called to read the rest of the line follow-
               ing `!'.

          $modifier
               Miscellaneous commands.  The available modifiers are:

               <f   Read commands from the file f and return.
               >f   Send output to the file f, which is created if it
                    does not exist.
               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 r5).  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

     ADB(1)                                                     ADB(1)

                    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. 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 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.  All signals are
                    turned on on entry to the subprocess.

               cs   The subprocess is continued with signal s c s, see
                    signal(2). If address is given then the subprocess
                    is continued at this address.  If no signal is
                    specified then the signal that caused the subpro-
                    cess 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.  Numbered
          variables are reserved for communication as follows.

     ADB(1)                                                     ADB(1)

          0    The last value printed.
          1    The last offset part of an instruction source.
          2    The previous value of variable 1.

          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 (0405, 0407, 0410 or 0411).
          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 triples (b1, e1, f1) and (b2,
          e2, f2) and the file address corresponding to a written
          address is calculated as follows.

             b1≦address<e1 => file address=address+f1-b1, 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 second triple is used.

          The initial setting of both mappings is suitable for normal
          a.out and core files.  If either file is not of the kind
          expected then, for that file, 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 val-
          ues are kept as signed 32 bit integers.

     FILES
          /dev/mem
          /dev/swap
          a.out
          core

     SEE ALSO
          ptrace(2), a.out(5), core(5)

     DIAGNOSTICS
          `Adb' when there is no current command or format.  Comments
          about inaccessible files, syntax errors, abnormal

     ADB(1)                                                     ADB(1)

          termination of commands, etc.  Exit status is 0, unless last
          command failed or returned nonzero status.

     BUGS
          A breakpoint set at the entry point is not effective on ini-
          tial entry to the program.
          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.