dbx.1

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.ns
.TP 15
\fBfunc \fR[\fIprocedure/function\fR]
Changes the current procedure or function to the one you specify. If you omit
\fIexpression\fR and \fIprocedure/function\fR, the debugger displays the name of the current procedure or function.
.IP
Changing the current function implicitly changes the current source file
to the one that contains the procedure or function; it also changes the current
scope used for name resolution.
.TP 15
\fBlist \fR[\fIsource-line-number\fR[:\fIinteger\fR]] 
.ns
.TP 15
\fBlist \fR[\fIsource-line-number\fR[\fB,\fI source-line-number\fR]]
.ns
.TP 15
\fBlist \fR[\fIprocedure/function\fR]
Lists the lines in the current source file.
.IP
If you specify a source line number and an integer, 
.PN dbx 
lists beginning from
\fIsource-line-number\fP and continuing for \fIinteger\fP number of
lines. If you omit \fIinteger\fP, the debugger displays 10 lines, by
default.
.IP
If you specify two source line numbers separated by a comma, 
the debugger begins the display at the first source line number
and continues through the second source line number. If you omit the
second source line number, the debugger displays 10 lines, by default.
.IP
If you specify a procedure or function name, the debugger displays lines
in that procedure or function. The debugger displays 10 lines be
default.
.IP
If you omit all arguments, the debugger begins the display at the
current line and displays 10 lines, by default.
.IP
The 
.B $listwindow 
debugger variable controls how many lines the debugger
displays. The default value for 
.B $listwindow 
is 10.
.TP 15
\fBtag \fItagname\fR
Sets the current source file or source line to the location specified by
\fItagname\fR.
.IP
You create tags using the
.PN ctags
command. See the
.MS ctags 1
reference page for more information. The debugger uses the tag file
named in the 
.B $tagfile 
debugger variable to resolve references to tags.
.TP 15
\fBuse \fR[\fIdirectory\fR...]
Displays or sets the list of directories that 
.PN dbx
uses when searching for source files. If you issue the \fBuse\fP command
without arguments, the debugger displays the list of directories it
searches for source files. To change the directory list, specify the
names of the directories you want on the list as arguments to the
.B use
command. The directories you specify replace any existing directory
list.
.TP 15
\fBwhatis \fIvariable\fR
Displays the type declaration for \fIvariable\fP.
.TP 15
\fBwhereis \fIvariable\fR
Displays the fully qualified name of each occurrence of \fIvariable\fP.
The order in which the debugger displays the qualified names is not
meaningful.
.TP 15
\fBwhich \fIvariable\fR
Displays the fully qualified name of \fIvariable\fP.
.SS Preparing for Program Execution
Before you execute your program under 
.PN dbx
control, you might want to perform setup tasks, such as changing the value of 
program variables, specifying 
what signals your program should recognize or ignore, and setting
breakpoints.
The following list describes the commands you use
to perform these tasks:
.TP 15
.B "assign \fIvariable = expression\fR"
Assigns the value of the specified expression to the specified program variable.
(Use the 
.B set
command to set the value of debugger variables.)
.TP 15
.B "catch \fR[\fIsignal\fR]"
Lists all signals that 
.PN dbx
catches, or, if you supply an argument, causes 
.PN dbx
to catch that signal. The signal you specify is added to the list of
signals 
.PN dbx
catches, so the debugger continues to catch any signals that were
already on its list. Some signals cannot be caught by any process. For a
list of signals and information on which signals can be caught,
see the 
.MS signal 3
reference page.
.TP 15
\fBignore \fR[\fIsignal\fR]
Lists all signals that 
.PN dbx
ignores.  If you specify a signal,
this command adds the signal to the list of signals the debugger
ignores. Some signals cannot be ignored by any process. For a list of
signals and information on which signals can be ignored, see the
.MS signal 3
reference page.
.TP 15
\fBstop \fIvariable\fR
.ns
.TP 15
\fBstop \fR[\fIvariable\fR] \fBat \fIsource-line\fR [\fBif \fIcondition\fR]
.ns
.TP 15
\fBstop \fR[\fIvariable\fR] \fBin \fIprocedure/function\fR \fR[\fBif \fIcondition\fR]
.ns
.TP 15
\fBstop \fR[\fIvariable\fR] \fBif \fIcondition\fR 
Stops execution when the specified variable changes value, the specified
source line is reached, the specified procedure or function is called, or the
specified condition is true. The condition must be a Boolean expression.
.IP
If you specify \fIvariable\fP with a source line number, the debugger
stops execution when the source line number is reached and the variable
changes value.  If you specify \fIvariable\fP with \fBin \fIprocedure/function\fR,
the debugger stops execution when it is executing in the named procedure
or function
and the named variable changes value.  With \fBif \fIcondition\fR, the
debugger stops execution when the condition is met and the variable
changes value.
.IP
If you specify a condition with \fBat \fIsource-line\fR or \fBin \fIprocedure/function\fR,
the debugger stops only if the condition is true.
.IP
The debugger associates an event number with each
.B stop
command you issue.  You use the event number to remove the breakpoint,
as described with the
.B delete 
command.
.TP 15
\fBtrace\fR [\fBat\fR] \fIsource-line\fR
.ns
.TP 15
\fBtrace\fR \fIprocedure/function\fR
.ns
.TP 15
\fBtrace \fIvariable \fR[\fBat \fIsource-line\fR] [\fBif \fIcondition\fR]
.ns
.TP 15
\fBtrace \fIvariable \fR[\fBin \fIprocedure/function\fR] [\fBif \fIcondition\fR]
Displays tracing information during program execution.  The 
.PN dbx
debugger associates an event number with each 
.B trace
command you issue. You use the event number to turn off tracing, as described with the
.B delete
command.
.IP
The first argument to the 
.B trace
command specifies what the debugger traces.  You can specify a source
line number, a procedure name, or a variable name.
.IP
If you specify a source line number, 
.PN dbx
displays the source line immediately prior to executing it. You can
specify a source line number in a source file that is not the current
one. To do so, precede the source line number with the source file name
in quotation marks (" ") followed by a colon (:), as shown in the following 
example:
.EX
(dbx) \f(CBtrace at "source_file.c":17\fP
.EE
The example specifies
tracing line 17 in
.PN source_file.c .
.IP
Specifying a procedure or function name causes 
.PN dbx
to display the name of the calling routine, the source line that
contains the call, and the parameters that are passed to the called
routine. In addition, 
.PN dbx
notes the return of the named procedure or function and displays the
return value, if any.  The debugger displays this information each time
the procedure or function is called.
.IP
Specifying a variable name causes
.PN dbx
to display the name and value of the variable each time it changes.
Program execution is substantially slower during this form of tracing.
.IP
If you specify the \fBin\fI procedure/function\fR clause, 
.PN dbx
displays tracing information only while executing the specified
procedure or function.
.IP
The \fIcondition\fP is a Boolean expression that
.PN dbx
evaluates prior to displaying any tracing information. The debugger
displays tracing information only if the condition is true.
.TP 15
\fBwhen \fR[\fIvariable\fR] [\fBat\fI line\fR] \fB{\fIcommand_list\fB}
.ns
.TP 15
\fBwhen \fR[\fIvariable\fR] [\fBin \fIprocedure/function\fR] \fB{\fIcommand_list\fB}
Executes the specified 
.PN dbx
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 \fIline\fR or
\fBin \fIprocedure\fR to control which occurrence of the variable causes
the debugger to execute the command list.
.SS Initiating Program Execution
The following 
.PN dbx
commands allow you to control program execution:
.TP 15
\fBcall \fIprocedure/function \fB(\fR[\fIparameters\fR]\fB)
Executes the object code associated with the named procedure or function.
This command passes the specified parameters to the procedure or function.
.TP 15
\fR[\fIn\fR] \fBcont \fR[\fIsignal\fR]
.ns
.TP 15
\fBcont \fR[\fIsignal\fR] \fBto \fIsource-line\fR
.ns
.TP 15
\fBcont \fR[\fIsignal\fR] \fBin \fIprocedure/function\fR
Continues execution 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 \fIsource-line\fR, the debugger continues execution until
it reaches the specified source line.
.IP
If you specify \fBin \fIprocedure/function\fR, the debugger resumes execution in
the named procedure or function.
./".TP 15
./".B debug \fR[\fIobject \fR[\fIcore\fR]]
./"Terminates the current debugging session and begins debugging
./"\fIobject\fP or displays the name of the current program. If you specify
./"\fIcore\fR, you can use the core file to determine the state of your
./"program.
./"When you use 
./".B debug
./"to begin a new debugging session, any options that you specified when you invoked 
./".PN dbx
./"remain in effect.  Similarly, any aliases,
./".PN dbx 
./"variables, or environment variables that were defined during the first
./"session remain unchanged.
./".IP
./"If you omit arguments for this command, the debugger displays the name
./"of the program you are currently debugging and that program's
./"arguments.
.TP 15
\fBgoto \fIsource-line\fR
Begins execution at the specified source line.
.TP 15
\fBnext \fR[\fIinteger\fR]
Executes up to the next source line. If the source line that is executed
contains a call to a procedure or function, the
.B next
command executes the entire procedure or function. Program execution
stops following the return from the procedure or function; that is, execution stops
prior to the source line that follows the call.
.IP
If you specify \fIinteger\fP, the debugger performs the specified number
of 
.B next
commands.
.TP 15
\fBrerun \fR[\fIarg1, arg2,...\fR] [\fB<\fIfile1\fR][\fB>\fIfile2\fR]
.ns
.TP 15
\fBrerun \fR[\fIarg1, arg2,...\fR] [\fB<\fIfile1][\fB>&\fIfile2\fR]
Reruns the program, using the same arguments that were specified with the 
\fBrun\fR command.  If you specify new arguments, \fBrerun\fR uses 
those arguments.
.IP
You can use angle brackets (< or >) to redirect input or output in the
usual manner.
.TP 15
\fBrun \fR[\fIarg1,arg2,...\fR] [\fB<\fIfile1\fR] [\fB>\fIfile2\fR]
.ns
.TP 15
\fBrun \fR[\fIarg1,arg2,...\fR] [\fB<\fIfile1\fR] [\fB>&\fIfile2\fR]
Runs the program, passing it the specified arguments.
.IP
You can use angle brackets (< or >) to redirect input or output in the
usual manner.
.TP 15
\fBreturn \fR[\fIprocedure/function\fR]
Executes until a return to \fIprocedure/function\fP is executed or until the
current procedure or function returns if you omit
\fIprocedure/function\fR.
.TP 15
\fBstep \fR[\fIinteger\fR]
Executes one source line. If the source line contains a call to a
procedure or function, the 
.B step
command stops at the first line of the procedure or function. (The
debugger does not stop at the first line of a procedure or function if
you compiled your program without using the
.B \-g
option.)
.IP
If you specify \fIinteger\fP, the debugger performs the specified number
of
.B step
commands.
.SS Examining Program State
The following commands help you determine the state of your program:
.TP 15
\fBdump \fR[\fIprocedure/function\fR] [\fI\&.\fR]
Displays variable information about the named procedure or function, or 
the current procedure or function if you do not specify one.  If you
specify dot (.),
the debugger displays information on 
all procedures or functions in the stack and their variables. 
.TP 15
\fBdown \fR[\fIexpression\fR]
Moves the current function down \fIcount\fP activation levels in the stack.  The
default is one level.
.TP 15
\fBup \fR[\fIexpression\fR]
Moves the current function up \fIcount\fP activation levels on the stack.  The default
is one level.
.TP 15
\fBprint \fIexpression1,expression2,\&.\&.\&.\fR
Displays the value of the specified expression.
.TP 15
\fBprintf \fI"format", arg1,arg2,...\fR
Formats a complex structure for display as specified. You use the same
format specifiers for this command as for the
.PN printf
subroutine. For information on specifying the format, see
.MS printf 3s .
(The 
.PN %s
conversion specification is not supported.)
.TP 15
\fBprintregs\fR
Displays all register values.
.TP 15
\fBwhere\fR [\fIn\fR]
Displays a list of the active procedures and functions. If you specify
\fIn\fR, the debugger displays only procedures and functions in the top \fIn\fP 
levels of the stack.
.SS Debugging at the Machine Level
You can use machine level commands to debug any program, regardless of
whether the program object file contains extended symbol table
information.
.PP
You can specify symbolic addresses by preceding the name with an
ampersand (&). You denote registers by \fB$r\fIN\fR, where \fIN\fR is the number of the
register. Addresses may be expressions made up of other addresses and the
operators plus (+), minus (-), and indirection (unary asterisk, *).
.PP
The following describes the
.PN dbx
machine level commands:
.TP 15
\fIaddress\fB/\fIcount\fR \fImode\fR
.ns
.TP
\fIaddress\fB?\fIcount\fR \fImode\fR
Searches forward (or backward, if you specify \fB?\fR) and displays
the contents of \fIaddress\fR or 
disassembles the code for the instruction \fIaddress\fR.
The \fIcount\fR argument specifies the number of items that the debugger displays at the
specified address.  The \fImode\fR determines how
.PN dbx
displays memory; if you omit it, the debugger uses the previous mode.
The initial mode is X. You can specify the following modes:
.sp 0
b	Displays a byte in octal.
.sp 0
c	Displays a byte as a character.
.sp 0
d	Displays a short word in decimal.
.sp 0
D	Displays a long word in decimal.
.sp 0
f	Displays a single precision real number.
.sp 0
g	Displays a double precision real number.
.sp 0
i	Displays machine instructions.
.sp 0
n	Displays data in typed format.
.sp 0
o	Displays a short word in octal.
.sp 0
O	Displays a long word in octal.
.sp 0
s	Displays a string of characters that ends in a null.
.sp 0
x	Displays a short word in hexadecimal.
.sp 0
X	Displays a long word in hexadecimal.
.IP
The debugger maintains the next address to be displayed in dot (.). 
To display the next address, you can use the
following command:
.EX
(dbx) \f(CB./\fP
.EE
The debugger will display the next \fIcount\fP locations in the
\fImode\fP specified in the previous command.
.TP 15
\fIaddress\fB/\fIcountL value mask\fR
Searches for a 32-bit word that satisfies the mask. The debugger starts
searching at the specified \fIaddress\fR.
The \fIcount\fR argument specifies the number of words the debugger
processes during the search.
.IP
The debugger masks the word stored at \fIaddress\fR 
using the value specified in 
\fImask\fR. If the masked value equals \fIvalue\fR, the debugger displays
the address of the masked value. Otherwise, the debugger increments
\fIaddress\fR and continues to search.
.TP 15