SDB(1) SDB(1)
NAME
sdb - symbolic debugger
SYNOPSIS
sdb [ objfil [ corfil [ directory ] ] ]
DESCRIPTION
Sdb is a symbolic debugger. It may examine source and/or
object files and provide a controlled environment for execu-
tion.
Objfil is an executable program file which has been compiled
with the -g (debug) option of cc, pascal, or f77(1). 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. Directory names the location of source
files, by default the current directory.
Sdb maintains a current line and a current file. If corfil
exists then they are initially set to the line and file con-
taining the source statement at which the process terminated
or stopped. Otherwise, they are set to the first line in
function main.
Names of variables are written just as they are in C, Pas-
cal, or Fortran. Variables local to a procedure may be
accessed using the form `procedure:variable'. If no proce-
dure name is given, the procedure containing the current
line is used by default. A member of a structure may be
referred to as `variable.member' or `variable->member'; an
array element as `variable[number]'. Combinations of these
forms may be used.
It is also possible to specify a variable by address. All
forms of integer constants which are valid in C may be used.
Line numbers in the source program are referred to as
`filename:number' or `procedure:number'. In either case the
number is relative to the beginning of the file. If no pro-
cedure or file name is given, the current file is used by
default. If no number is given, the first line of the named
procedure or file is used.
The commands for examining data are:
t Print a stack trace of the terminated or stopped pro-
gram.
T Print the top line of the stack trace.
SDB(1) SDB(1)
variable/lm
Print the value of variable according to length l and
format m. If l and m are omitted, sdb chooses a length
and format suitable for the variable's type as declared
in the program. The length specifiers are:
b one byte
h two bytes (half word)
l four bytes (long word)
number
string length for formats s and a
Legal values for m are:
c character
d decimal
u decimal, unsigned
o octal
x hexadecimal
f 32 bit single precision floating point
g 64 bit double precision floating point
s Assume variable is a string pointer and print
characters until a null is reached.
a Print characters starting at the variable's
address until a null is reached.
p pointer to procedure
The length specifiers are only effective with the for-
mats d, u, o and x. If one of these formats is speci-
fied and l is omitted, the length defaults to the word
length of the host machine: 4 for the VAX. The last
variable may be redisplayed with the command `./'. The
sh(1) metacharacters * and ? may be used within proce-
dure and variable names, providing a limited form of
pattern matching. If no procedure name is given, both
variables local to the current procedure and global
(common for f77) variables are matched. If a procedure
name is specified, only variables local to that proce-
dure are matched. The form `:pattern' matches only
global variables (blank common for f77),. The name of
a common block may be specified instead of a procedure
name for f77 programs.
variable=lm
linenumber=lm
number=lm
Print the address of the variable or line number or the
value of the number in the specified format. If no
format is given, then `lx' is used. The last variant
of this command provides a convenient way to convert
between decimal, octal and hexadecimal.
SDB(1) SDB(1)
variable!value
Set the variable to the given value. The value may be
a number, character constant or a variable. If the
variable is of type float or double, the value may also
be a floating constant.
The commands for examining source files are
e procedure
e filename.c
Set the current file to the file containing the named
procedure or the named filename. Set the current line
to the first line in the named procedure or file. If
no procedure or file name is given, the current proce-
dure and file names are reported.
/regular expression/
Search forward from the current line for a line con-
taining a string matching the regular expression as in
ed(1). The trailing `/' may be elided.
?regular expression?
Search backward from the current line for a line con-
taining a string matching the regular expression as in
ed(1). The trailing `?' may be elided.
p Print the current line.
z Print the current line followed by the next 9 lines.
Set the current line to the last line printed.
control-D
Scroll. Print the next 10 lines. Set the current line
to the last line printed.
w Window. Print the 10 lines around the current line.
number
Set the current line to the given line number. Print
the new current line.
count +
Advance the current line by count lines. Print the new
current line.
count -
Retreat the current line by count lines. Print the new
current line.
The commands for controlling the execution of the source
program are:
SDB(1) SDB(1)
count r args
count R
Run the program with the given arguments. The r com-
mand with no arguments reuses the previous arguments to
the program while the R command runs the program with
no arguments. An argument beginning with `<' or `>'
causes redirection for the standard input or output
respectively. If count is given, it specifies the num-
ber of breakpoints to be ignored.
linenumber c count
linenumber C count
Continue after a breakpoint or interrupt. If count is
given, it specifies the number of breakpoints to be
ignored. C continues with the signal which caused the
program to stop and c ignores it. If a linenumber is
given then a temporary breakpoint is placed at the line
and execution is continued. The breakpoint is deleted
when the command finishes.
count s
Single step. Run the program through count lines. If
no count is given then the program is run for one line.
count S
Single step, but step through subroutine calls.
k Kill the debugged program.
procedure(arg1,arg2,...)
procedure(arg1,arg2,...)/m
Execute the named procedure with the given arguments.
Arguments can be integer, character or string constants
or names of variables accessible from the current pro-
cedure. The second form causes the value returned by
the procedure to be printed according to format m. If
no format is given, it defaults to `d'.
linenumber b commands
Set a breakpoint at the given line. If a procedure
name without a line number is given (e.g. `proc:'), a
breakpoint is placed at the first line in the procedure
even if it was not compiled with the debug flag. If no
linenumber is given, a breakpoint is placed at the cur-
rent line.
If no commands are given then execution stops just
before the breakpoint and control is returned to sdb.
Otherwise the semicolon-separated commands are executed
when the breakpoint is encountered and execution con-
tinues.
linenumber d
SDB(1) SDB(1)
Delete a breakpoint at the given line. If no linenum-
ber is given, each breakpoint location is printed and a
line is read from the standard input. If the line
begins with a `y' or `d' then the breakpoint is
deleted.
B Print a list of the currently active breakpoints.
D Delete all breakpoints.
l Print the last executed line.
linenumber a
Announce. If linenumber is of the form `proc:number',
the command does a `linenumber b l'. If linenumber is
of the form `proc:', the command does a `proc: b T'.
Miscellaneous commands.
! command
The command is interpreted by sh(1).
newline
If the previous command printed a source line then
advance the current line by 1 line and print the new
current line. If the previous command displayed a core
location then display the next core location.
" string
Print the given string.
q Exit the debugger.
The following commands are intended for debugging the debug-
ger.
V Print the version number.
X Print a list of procedures and files being debugged.
Y Toggle debug output.
FILES
a.out
core
DIAGNOSTICS
Error reports are either identical to those of adb(1) or are
self-explanatory.
SEE ALSO
SDB(1) SDB(1)
adb(1), pi(9.1), coreid(1)
BUGS
If a procedure is called when the program is not stopped at
a breakpoint (such as when a core image is being debugged),
all variables are initialized before the procedure is
started. This makes it impossible to use a procedure to
extract data from a core image.
Arrays must be of one dimension and of zero origin to be
correctly addressed.
The default type for printing Fortran parameters is incor-
rect: address instead of value.
Tracebacks containing Fortran subprograms with multiple
entry points may print too many arguments in the wrong
order, but their values are correct.
Sdb understands Pascal, but not its types.
The meaning of control-D is nonstandard