term% cat index.txt ADB(1) General Commands Manual 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 examined. The default for objfil is
‘a.out'. Corfil is assumed to be a core image file produced after exe‐
cuting 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. 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 ex‐
pressions.
EXPRESSIONS
. The value of dot.
+ The value of dot incremented by the current increment.
^ The value of dot decremented by the current increment.
" The last address typed.
integer
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 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 hexadecimal digits are 0123456789abcdefABCDEF
with the obvious values. Note that a hexadecimal number whose
most significant digit would otherwise be an alphabetic charac‐
ter must have a 0x (or 0X) prefix (or a leading zero if the de‐
fault radix is hexadecimal).
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
corfil. The register names are those printed by the $r command.
symbol A symbol is a sequence of upper or lower case letters, under‐
scores or digits, not starting with a digit. \f[R] 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.
_ symbol
In C, the ‘true name' of an external symbol begins with _. It
may be necessary to utter this name to disinguish it from inter‐
nal 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 cor‐
responding to routine; if routine is omitted, the active proce‐
dure is assumed.
(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.'
%exp If exp is used as an address, it is in register space; see AD‐
DRESSES .
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 modi‐
fiers. 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 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 incremented by the amount given for each format
letter. If no format is given then the last format is used. The for‐
mat letters available are as follows.
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 character 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 oc‐
cupied 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.
newline
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 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 com‐
mand 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.)
>name Dot is assigned to the variable or register named.
! A shell 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 exe‐
cuted in a file, further commands in the file are not
seen. If f is omitted, the current input stream is ter‐
minated. 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 de‐
fault if modifier is omitted.
r Print the general registers and the instruction addressed
by pc. Dot is set to pc.
R Like $r, but include boring registers like the kernel
stack pointer.
b Print all breakpoints and their associated counts and
commands.
c C stack backtrace. If address is given then it is taken
as the address of the current frame (instead of fp). If
C is used then the names and (32 bit) values of all para‐
meters, automatic and static variables are printed for
each active function. If count is given then only the
first count frames are printed.
d Set the default radix to address and report the new
value. Address is interpreted in the (old) current
radix; ‘10$d' never changes the default radix. To make
decimal the default radix, use ‘0t10$d'. A radix of zero
is a special case: input with a leading zero is octal,
that with a leading sharp-sign ‘#' is hexadecimal, other
numbers are decimal; output is hexadecimal by default;
hex and octal numbers are printed with a leading # and 0
respectively.
e The names and values of external variables are printed.
w Set the page width for output to address (default 80).
s Set the limit for symbol matches to address (default
255).
q Exit from adb.
v Print all non zero variables in the current radix.
m Print the address maps.
k Simulated VAX memory management: set the system base reg‐
ister pointer to address. System space addresses will
hereafter be mapped according to the system page table.
If address is zero, mapping is turned off.
p Set the PCB base pointer to address, which may be either
the physical address of a process control block (as found
in the PCBB register) or the system space address of a
page table entry which points to a PCB (as found in
p_addr). User space addresses will hereafter be trans‐
lated according to the user page tables pointed to by the
PCB. Kernel mapping ($k) must already be in effect. If
address is zero, user mapping is turned off; addresses
less than 0x80000000 will be treated as physical ad‐
dresses.
$k and $p are useful for system debugging.
:modifier
Manage a subprocess. Available modifiers are:
bc Set breakpoint at address. 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 explic‐
itly 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 sup‐
plied 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 skip‐
ping 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 cur‐
rent 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.
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.
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.
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
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 ad‐
dress 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 process 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 re‐
spectively. ?* tries for data space (in objfil); /* accesses instruc‐
tion space (in corfil).
Registers in process and core images are a special case; they live in a
special ‘register' address space. The contents of register 0 are lo‐
cated 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 $p commands) are
done before the mapping described above.
So that adb may be used on large files all appropriate values are kept
as signed 32 bit integers.
FILES
a.out
core
/usr/lib/adb/* parameter files
SEE ALSO
pi(9.1), sdb(1), proc(4), a.out(5), core(5)
DIAGNOSTICS
‘Adb' when there is no current command or format. Comments about inac‐
cessible files, syntax errors, abnormal termination of commands, etc.
Exit status is 0, unless last command failed or returned nonzero sta‐
tus.
BUGS
Either the explanation or the implementation of register variables is
too complex and arcane.
0$d should probably be the default.
ADB(1)