dbx.1

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\fR[\fIn\fR] \fBconti \fR[\fIsignal\fR]
.ns
.TP 15
\fBconti \fR[\fIsignal\fR] \fBto \fIaddress\fR
.ns
.TP 15
\fBconti \fR[\fIsignal\fR] \fBin \fIprocedure/function\fR
Continues execution of assembly code from where it stopped.  If you specify an integer \fIn\fP, the
debugger ignores that number of stops after it resumes program
execution.
If you specify \fIsignal\fR, the process continues as though it received
the signal.  
.IP
If you specify \fBto\fI address\fR, the debugger continues execution until
it reaches the specified address.
.IP
If you specify \fBin \fIprocedure/function\fR, the debugger resumes execution in
the named procedure or function.
.TP 15
\fBnexti \fR[\fIinteger\fR]
Executes up to the next machine instruction. If the machine instruction
that
.PN dbx
executes contains a call to a procedure or function, the debugger
executes the entire procedure or function. Program execution stops
following the return from the procedure; that is, execution stops prior
to execution of the machine instruction that follows the call.
.IP
If you specify an integer, the debugger performs \fIinteger\fP 
.B nexti
instructions.
.TP 15
\fBstepi \fR[\fIinteger\fR]
Executes the specified number of machine instructions.  If one of the
machine instructions contains a call to a procedure or function, the
debugger stops at the first line of the procedure or function.
The default is to execute one instruction.
.TP
\fBstopi\fR \fIvariable\fR
.ns
.TP 15
\fBstopi\fR \fR[\fIvariable\fR] [\fBat\fR \fIaddress\fR] [\fBif \fIcondition\fR]
.ns
.TP 15
\fBstopi \fR[\fIvariable\fR] \fR[\fBin \fIprocedure/function\fR] \fR[\fBif \fIcondition\fR]
Stops when the specified variable changes value, the specified address
is reached, the specified condition is true, or the specified procedure
or function is reached. 
.IP
By combining the arguments, you can cause the debugger to stop, for
example, only when the occurrence of \fIvariable\fP at the specified
address changes value and \fIcondition\fP is true.
.TP 15
\fBtracei \fIvariable\fR \fR[\fBat \fIaddress\fR] [\fBif \fIexpression\fR]
.ns
.TP 15
\fBtracei \fIvariable\fR [\fBin \fIprocedure/function\fR] \fR[\fBat \fIaddress\fR] [\fBif \fIexpression\fR]
.ns
.TP 15
\fBtracei \fIaddress\fR [\fBif \fIcondition\fR]
Traces the value of \fIvariable\fP or the execution of a particular
address. 
.IP
When you trace the value of a variable, you can use \fBat \fIaddress\fR,
\fBin \fIprocedure/function\fR, and \fBif \fIcondition\fR to control the
specific variable that is traced.
.IP
You can specify a condition when you trace the execution of an address.
The debugger displays tracing information only when the condition is
true.
.TP 15
\fBwheni \fR[\fIvariable\fR] [\fBat\fI address\fR] \fB{\fIcommand_list\fR\fB}
.ns
.TP 15
\fBwheni \fR[\fIvariable\fR] [\fBin \fIprocedure/function\fR] \fB{\fIcommand_list\fR\fB}
Executes the specified 
.PN dbx
machine command list. You can separate the commands by commas (,) or
semi-colons (;).
.IP
If you specify \fIvariable\fP, the debugger executes the command list
when the value of the variable changes. Specify \fBat \fIaddress\fR or
\fBin \fIprocedure\fR to control which occurrence of the variable causes
the debugger to execute the command list.
.SS Predefined dbx Variables
The debugger contains variables that control certain aspects of its
operations. Some debugger variables are used internally by
.PN dbx .
You must not change the value of those variables. The debugger allows you
to change the values of other variables using the
.B set
and
.B unset
commands. The following list describes the debugger variables you can
control:
.TP 15
.B $addrfmt
Specifies the format for addresses.  You can set this variable to any
format that you can use with the
.PN printf
function, except %s because the
.PN %s
conversion specification is not supported by
.PN dbx . 
See the
.MS printf 3s
reference page for information on valid formats. By default, this
variable is set to
.PN 0x%x ,
which specifies hexadecimal format.
.TP 15
.B $casesense
When set to a nonzero value, specifies that uppercase and lowercase
letters be treated as different characters during a search.  When set to zero,
.PN dbx
ignores the case of letters.  The default is zero.
.TP 15
.B $datacache
Caches information from the data space so that 
.PN dbx
must access the data space only once. If this variable is set to zero, the
debugger does not cache data space. If your program contains any data
declared as 
.PN volatile ,
.PN dbx
automatically sets this variable to zero. To debug the operating
system, set this variable to zero; otherwise, set it to a 
nonzero value.  The default is a nonzero value.
.TP 15
.B $dispix
Causes the debugger to be in the correct mode to debug pixie code.  When set to zero, the debugger displays
machine code while debugging.  When set to a nonzero value, the debugger displays pixie code.
The default is zero.
.TP 15
.B $hexchars
When set to a nonzero value, causes the debugger to display characters in hexadecimal format.
.TP 15
.B $hexin
When set to a nonzero value, causes the debugger to interpret input constants as hexadecimal. When set, this variable overrides the 
.B $octin 
variable.
.TP 15
.B $hexints
When set to a nonzero value, changes the default output constants
to hexadecimal.  When set, this variable overrides the 
.B $octints 
variable.
.TP 15
.B $hexstrings
When set to a nonzero value, causes the debugger to display all strings 
in hexadecimal format. When set to zero, causes the debugger to display
strings in character format.
.TP 15
.B $historyevent
Stores the current history line.
.TP 15
.B $lines
Determines how many lines the debugger stores in its history list.
The default is 20 lines.
.TP 15
.B $listwindow
Specifies how many lines the \fBlist\fR command displays.
.TP 15
.B $main
Specifies the name of the procedure or function that 
.PN dbx
begins when running the process.  The debugger can begin a process at any procedure
or function. By default, the debugger begins a process at a procedure
named main.
.TP 15
.B $maxstrlen
Specifies how many characters of a string 
.PN dbx
displays for pointers to strings.  The default is 128 characters.
.TP 15
.B $octin
When set to a nonzero value, changes the default input constants to octal.
When set, the 
.B $hexin 
variable overrides this variable.
.TP 15
.B $octints
When set to a nonzero value, causes 
.PN dbx
to display integers in octal format. When set, the 
.B $hexints 
variable
overrides this variable.
.TP 15
.B $page
Specifies whether to page long information.  A nonzero value turns on paging;
a zero turns it off.  The default is one.
.TP 15
.B $pagewindow
Specifies how many lines the debugger displays when information runs longer than
one screen.  You can change this variable to match the number of lines
on any terminal.  If set to zero, this variable assumes one line.
The default is 22, leaving space for a continuation query.
.TP 15
.B $printwhilestep
Determines whether the debugger displays source lines or instructions
when executing the 
\fBstep\fR[\fIn\fR] and
\fBstepi\fR[\fIn\fR] commands.
When set to a nonzero value,  
causes
.PN dbx
to display all \fIn\fR lines or
instructions. When set to zero, causes 
.PN dbx 
to display only
the last line or instruction.  The default
is zero.
.TP 15
.B $pimode
Displays input when used with the \fBplayback input\fR command.
The default is zero.
.TP 15
.B $printdata
When set to a nonzero value, causes the debugger to display the contents of 
registers next to each 
instruction it displays. The debugger displays the registers used by the
instruction. The default is zero.
.TP 15
.B $printwide
When set to a nonzero value, causes the debugger to display the contents of variables
in a horizontal format. 
The default is zero.
.TP 15
.B $prompt
Sets the prompt for 
.PN dbx .
.TP 15
.B $readtextfile
When set to a nonzero value, 
causes
.PN dbx 
to read instructions from the object file 
rather than the process.  
This variable should always be set to zero when the process being
debugged copies in code during the debugging process.
The default is a nonzero value. 
.TP 15
.B $regstyle
When set to a nonzero value, causes the debugger to display registers during
disassembly in their
normal \fIr\fR format (r0,r1,\&.\&.\&.r31).   When set to zero, causes the
debugger to display registers 
in a special format (zero, at, v0, v1,...), which is commonly used in debugging
programs written in assembly language. The default is a nonzero value.
.IP
Setting this variable does not affect how the debugger displays the
names of register when you issue the
.B printregs
command. This variable affects the debugger's machine level commands.
.TP 15
.B $repeatmode
When set to a nonzero value, 
causes
.PN dbx
to repeat the previous command if you press the
Return key at the 
.PN dbx 
prompt.
The default is a nonzero value.
.TP 15
.B $rimode
When set to a nonzero value, causes the debugger to record input while recording output.  
The default is zero. 
.TP 15
.B $sigvec
Tells 
.PN dbx 
the name of the code called by the system to invoke user 
signal handlers.  This variable is set to \fRsigvec\fR on ULTRIX systems.
.TP 15
.B $symtotal
Stores the number of symbols that
.PN dbx
loads for the process you are debugging.
.TP 15
.B $tagfile
Names the file that contains tags for the current program. The
.B tag
and
.B tagvalue
commands search the named file to resolve references to tags. For more
information on using tag files, see
.MS ctags 1 .
./".SS Predefined dbx Aliases
./"The debugger has the following predefined aliases:
./".TP 15
./"\fB?\fR
./"Prints a list of all 
./".PN dbx
./"commands.
./".TP 15
./"\fBa\fR
./"Assigns a value to a program variable.
./".TP 15
./"\fBb\fR
./"Sets a breakpoint at a specified line.
./".TP 15
./"\fBbp\fR
./"Stops in a specified procedure or function.
./".TP 15
./"\fBc\fR
./"Continues program execution after a breakpoint.
./".TP 15
./"\fBd\fR
./"Deletes the specified item from the status list.
./".TP 15
./"\fBe\fR
./"Looks at the specified file.
./".TP 15
./"\fBf\fR
./"Moves to the specified activation level on the stack.
./".TP 15
./"\fBg\fR
./"Goes to the specified line and begins executing the program there.
./".TP 15
./"\fBh\fR
./"Lists all items currently on the history list.
./".TP 15
./"\fBj\fR
./"Shows what items are on the status list.
./".TP 15
./"\fBl\fR
./"Lists the next 10 lines of source code.
./".TP 15
./"\fBli\fR
./"Lists the next 10 machine instructions.
./".TP 15
./"\fBn\fR or \fBS\fR
./"Step over the specified number of lines without stepping into procedures
./"or functions.
./".TP 15
./"\fBni\fR or \fRSi\fR
./"Step over the specified number of assembly code instructions without 
./"stepping into procedure calls.
./".TP 15
./"\fBp\fR
./"Prints the value of the specified expression or variable.
./".TP 15
./"\fBpd\fR
./"Prints the value of the specified expression or variable in decimal.
./".TP 15
./"\fBpi\fR
./"Replays 
./".PN dbx
./"commands that were saved with the \fBrecord
./"input\fR command.
./".TP 15
./"\fBpo\fR
./"Prints the value of the specified expression or variable in octal.
./".TP 15
./"\fBpr\fR
./"Prints values for all registers. 
./".TP 15
./"\fBpx\fR
./"Prints the value for the specified variable or expression in hexadecimal.
./".TP 15
./"\fBq\fR
./"Ends the debugging session.
./".TP 15
./"\fBr\fR
./"Runs the program again with the same arguments that were specified with the
./"\fBrun\fR command.
./".TP 15
./"\fBri\fR
./"Records in a file every command typed.
./".TP 15
./"\fBro\fR
./"Records all debugger output in the specified file.
./".TP 15
./"\fBs\fR
./"Steps the next number of specified lines.
./".TP 15
./"\fBsi\fR
./"Steps the next number of specified lines of assembly code instructions.
./".TP 15
./"\fBt\fR
./"Does a stack trace.
./".TP 15
./"\fBu\fR
./"Lists the previous 10 lines.
./".TP 15
./"\fBw\fR
./"Lists the 5 lines preceding and following the current line.
./".TP 15
./"\fBW\fR
./"Lists the 10 lines preceding and following the current line.
./".TP 15
./"\fBwi\fR
./"Lists the 5 machine instructions preceding and following the 
./"machine instruction.
.SH Restrictions
The \fBprintf\fR debugger command does not support the
.PN %s 
conversion specification.
.PP
The 
.PN dbx
debugger does not allow you to run a program you do not own unless
you are logged in as root. If you are not root, the following message
might be displayed on your screen when you issue the 
.B run
command:
.EX
cannot write to address \fIaddress\fP in process \fIproc-number\fP
.EE
In the message it displays,
the debugger replaces \fIaddress\fR with the address to which it could
not write and \fIproc-number\fR with the number of the process that contains
that address.
This message is displayed when the
.PN dbx
debugger tries to set breakpoints because of restrictions on the
.PN ptrace
system call. The
.PN dbx
debugger always tries to set a breakpoint on exit. If you repeat the 
.PN run
command, your program runs without breakpoints. 
.SH Files
.TP 15
.PN a.out
Object file
.TP
.PN core
Core dump file
.TP
.PN \&.dbxinit
Initialization file
.SH See Also
ac(1), cc(1), ctags(1), f77(1), pc(1), pcc(1), pixie(1), vi(1), signal(3),
printf (3s)
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