dbx

<B>Digital的Unix操作系统VAX 4.2源码</B>

Changing the current function implicitly changes the current source file
to the one that contains the function; it also changes the current scope
used for name resolution.
.IP "\fBlist\fP [\fIsource-line-number\fP [\fB,\fP \fIsource-line-number\fP]]"
.ns
.IP "\fBlist\fP \fIprocedure/function\fP"
List the lines in the current source file from the first line number to
the second inclusive.
If no lines are specified, the next 10 lines are listed.
If the name of a procedure or function is given
lines \fIn-k\fP to \fIn+k\fP are listed where \fIn\fP is the first statement
in the procedure or function and \fIk\fP is small.
.IP "\fBuse\fP \fIdirectory-list\fP"
Set the list of directories to be searched
when looking for source files.
.sp 1
.br
.ne 8v
.PP
.B Machine Level Commands
.sp 1
.TP
\fBtracei\fP [\fIaddress\fP] [\fBif\fP \fIcond\fP]
.ns
.TP
\fBtracei\fP [\fIvariable\fP] [\fBat\fP \fIaddress\fP] [\fBif\fP \fIcond\fP]
.ns
.TP
\fBstopi\fP [\fIaddress\fP] [\fBif\fP \fIcond\fP]
.ns
.TP
\fBstopi\fP [\fBat\fP] [\fIaddress\fP] [\fBif\fP \fIcond\fP]
Turn on tracing or set a stop using a machine instruction address.
.TP
\fBstepi\fP
.ns
.TP
\fBnexti\fP
Single step as in \fBstep\fP or \fBnext\fP, but do a single instruction
rather than source line.
.TP
\fIaddress\fP \fB,\fP\fIaddress\fP\fB/\fP [\fImode\fP]
.ns
.TP
[\fIaddress\fP] \fB/\fP [\fIcount\fP] [\fImode\fP]
Print the contents of memory starting at the first \fIaddress\fP
and continuing up to the second \fIaddress\fP or until \fIcount\fP items are printed.
If no address is specified, the address following the one
printed most recently is used.
The \fImode\fP specifies how memory is to be printed;
if it is omitted the previous mode specified is used.
The initial mode is ``X''.
The following modes are supported:
.nr In 5
.in +\n(Inn
.ta \n(Inn
.br
.nr wg 1v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBi\fP	\c
print the machine instruction
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBd\fP	\c
print a short word in decimal
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBD\fP	\c
print a long word in decimal
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBo\fP	\c
print a short word in octal
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBO\fP	\c
print a long word in octal
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBx\fP	\c
print a short word in hexadecimal
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBX\fP	\c
print a long word in hexadecimal
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBb\fP	\c
print a byte in octal
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBc\fP	\c
print a byte as a character
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBs\fP	\c
print a string of characters terminated by a null byte
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBf\fP	\c
print a single precision real number
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\fBg\fP	\c
print a double precision real number
.in -\n(Inn
.br
.nr wg 1v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.PP
Symbolic addresses are specified by preceding the name with an ``&''.
Registers are denoted by ``$rN'' where N is the number of the register.
Addresses may be expressions made up of other addresses and
the operators ``+'', ``-'', and indirection (unary ``*'').
.sp 1
.br
.ne 8v
.PP
.B Miscellaneous Commands
.sp 1
.IP "\fBsh\fP \fIcommand-line\fP"
Pass the command line to the shell for execution.
The SHELL environment variable determines which shell is used.
.IP "\fBalias\fP \fInew-command-name\fP \fIold-command-name\fP"
Respond to \fInew-command-name\fP
as though it were \fIold-command-name\fP.
.IP \fBhelp\fP
Print out a synopsis of \fI\*(dB\fP commands.
.IP \fBgripe\fP
Invoke a mail program to send a message to the person in charge of \fI\*(dB\fP.
.TP
\fBsource\fP \fIfilename\fP
Read \fI\*(dB\fP commands from the given \fIfilename\fP.
.IP "\fBquit\fP"
Exit \fI\*(dB\fP.
.SH FILES
.nr In 20
.in +\n(Inn
.ta \n(Inn
.br
.nr wg 1v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&a.out	\c
object file
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.ti -\n(Inn
\&\&.\*(dBinit	\c
initial commands
.br
.nr wg 0v
.ie \n(.h=\n(vk .nr wg -\n(vhu
.el .nr vh 0
.if \n(wg>0 \{\
.sp \n(wgu
.nr vh +\n(wgu \}
.nr vk \n(.h
.SH SEE ALSO
cc(1), f77(1), mod(l)
.SH COMMENTS
Non-local gotos can cause some trace/stops to be missed.
Most of the command names are too long.
The alias facility helps, but is really quite weak.
A \fIcsh\fP-like history capability would improve the situation.
But then, who wants to duplicate the c-shell in a debugger?
.PP
\fI\*(DB\fP suffers from the same ``multiple include'' malady as does sdb.
If you have a program consisting of a number of object files
and each is built from source files that include header files,
the symbolic information for the header files is replicated in
each object file.
Since about one debugger start-up is done for each link,
having the linker (ld) re-organize the symbol information
won't save much time, though it would reduce some of the
disk space used.
The problem is an artifact of the unrestricted semantics
of #include's in C; for example an include file can contain
static declarations that are separate entities for each file
in which they are included.