10564b1175
groff 1.23.0 added .MR to its -man macro package. The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020." From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.
Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.
Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized. groff's .MR does not. This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.
533 lines
11 KiB
Groff
533 lines
11 KiB
Groff
.TH ACID 1
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.SH NAME
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acid, acidtypes \- debugger
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.SH SYNOPSIS
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.B acid
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[
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.BI -l " library
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]
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[
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.B -wq
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] [
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.B -m
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.I machine
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] [
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.I pid
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.I core
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]
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[
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.I textfile
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]
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.PP
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.B acidtypes
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[
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.B -p
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.I prefix
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]
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.I file
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\&...
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.\" .PP
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.\" .B acid
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.\" .B -l
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.\" .B truss
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.\" .I textfile
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.\" .PP
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.\" .B acid
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.\" .B -l
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.\" .B trump
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.\" [
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.\" .I pid
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.\" ]
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.\" [
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.\" .I textfile
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.\" ]
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.SH DESCRIPTION
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.I Acid
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is a programmable symbolic debugger.
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It can inspect one or more processes that share an address space.
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A program to be debugged may be specified by the process id of
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a running or defunct process,
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or by the name of the program's text file
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.RB ( a.out
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by default).
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At the prompt,
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.I acid
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will store function definitions or print the value of expressions.
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Options are
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.TP .9i
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.B -w
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Allow the textfile to be modified.
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.TP
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.B -q
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Print variable renamings at startup.
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.TP
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.BI -l " library
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Load from
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.I library
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at startup; see below.
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.TP
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.BI -m " machine
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Assume instructions are for the given CPU type
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(see
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.MR mach 3 )
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instead of using the executable header to select
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the CPU type.
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.TP
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.BI -k
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Debug the kernel state for the process, rather than the user state.
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.PP
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At startup,
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.I acid
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obtains standard function definitions from the library file
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.BR \*9/acid/port ,
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architecture-dependent functions from
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.BR \*9/acid/$objtype ,
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user-specified functions from
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.BR $HOME/lib/acid ,
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and further functions from
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.B -l
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files.
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Definitions in any file may override previously defined functions.
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If the function
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.IR acidinit ()
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is defined, it will be invoked after all modules have been loaded.
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Then the function
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.IR acidmap ()
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will be invoked if defined.
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.B \*9/acid/port
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provides a definition of
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.I acidmap
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that attaches all the shared libraries being used by the target process
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and then runs
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.I acidtypes
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.RI ( q.v. )
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to create
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.I acid
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functions for examining data structures.
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.SS Language
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Symbols of the program being debugged become integer
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variables whose values are addresses.
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Contents of addresses are obtained by indirection.
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Local variables are qualified by
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function name, for example
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.BR main:argv .
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When program symbols conflict with
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.I acid
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words, distinguishing
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.B $
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signs are prefixed.
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Such renamings are reported at startup; option
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.B -q
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suppresses them.
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.PP
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Variable types
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.RI ( "integer, float, list, string" )
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and formats are inferred from assignments.
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Truth values false/true are attributed to zero/nonzero
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integers or floats and to empty/nonempty lists or strings.
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Lists are sequences of expressions surrounded by
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.BR {\^}
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and separated by commas.
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.PP
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Expressions are much as in C,
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but yield both a value and a format.
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Casts to complex types are allowed.
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Lists admit the following operators, with
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subscripts counted from 0.
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.IP
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.BI head " list
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.br
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.BI tail " list
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.br
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.BI append " list", " element
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.br
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.BI delete " list", " subscript
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.PP
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Format codes are the same as in
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.MR db 1 .
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Formats may be attached to (unary) expressions with
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.BR \e ,
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e.g.
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.BR (32*7)\eD .
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There are two indirection operators,
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.B *
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to address a core image,
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.B @
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to address a text file.
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The type and format of the result are determined by the format of the operand,
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whose type must be integer.
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.PP
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Statements are
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.IP
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.BI if " expr " then " statement " "\fR[ \fPelse\fI statement \fR]
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.br
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.BI while " expr " do " statement
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.br
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.BI loop " expr" , " expr " do " statement
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.br
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.BI defn " name" ( args ") {" " statement \fP}
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.br
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.BI defn " name"
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.br
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.IB name ( args )
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.br
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.BI builtin " name" ( args )
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.br
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.BI local " name
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.br
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.BI return " expr
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.br
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.BR whatis " [ \fI name \fP]
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.PP
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The statement
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.B defn
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.I name
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clears the definition for
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.IR name .
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A
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.B defn
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may override a built-in function;
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prefixing a function call with
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.B builtin
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ignores any overriding
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.BR defn ,
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forcing the use of the built-in function.
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.PP
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Here is a partial list of functions; see the manual for a complete list.
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.TF asm(address)
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.TP
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.B stk()
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Print a stack trace for current process.
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.TP
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.B lstk()
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Print a stack trace with values of local variables.
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.TP
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.B gpr()
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Print general registers.
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Registers can also be accessed by name, for example
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.BR *R0 .
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.TP
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.B spr()
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Print special registers such as program counter and stack pointer.
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.TP
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.B fpr()
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Print floating-point registers.
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.TP
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.B regs()
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Same as
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.BR spr();gpr() .
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.TP
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.BI fmt( expr , format )
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Expression
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.I expr
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with format given by the character value of expression
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.IR format .
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.TP
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.BI src( address )
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Print 10 lines of source around the program address.
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.TP
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.BI Bsrc( address )
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Get the source line for the program address
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into a window of a running
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.MR sam 1
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and select it.
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.TP
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.BI line( address )
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Print source line nearest to the program address.
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.TP
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.B source()
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List current source directories.
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.TP
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.BI addsrcdir( string )
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Add a source directory to the list.
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.TP
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.BI filepc( where )
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Convert a string of the form
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.IB sourcefile : linenumber
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to a machine address.
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.TP
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.BI pcfile( address )
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Convert a machine address to a source file name.
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.TP
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.BI pcline( address )
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Convert a machine address to a source line number.
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.TP
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.BI bptab()
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List breakpoints set in the current process.
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.TP
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.BI bpset( address )
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Set a breakpoint in the current process at the given address.
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(Doesn't work on Unix yet.)
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.TP
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.BI bpdel( address )
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Delete a breakpoint from the current process.
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.TP
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.B cont()
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Continue execution of current process and wait for it to stop.
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.TP
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.B step()
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Execute a single machine instruction in the current process.
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(Doesn't work on Unix yet.)
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.TP
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.B func()
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Step repeatedly until after a function return.
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.TP
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.BI stopped( pid )
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This replaceable function is called automatically when the given process
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stops.
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It normally prints the program counter and returns to the prompt.
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.TP
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.BI asm( address )
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Disassemble 30 machine instructions beginning at the given address.
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.TP
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.BI mem( address , string )
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Print a block of memory
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interpreted according to a string of format codes.
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.TP
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.BI dump( address , n , string\fP)
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Like
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.BR mem (),
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repeated for
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.I n
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consecutive blocks.
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.TP
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.BI print( expr , ... )
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Print the values of the expressions.
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.TP
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.BI newproc( arguments )
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Start a new process with arguments given as a string
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and halt at the first instruction.
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.TP
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.B new()
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Like
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.IR newproc (),
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but take arguments (except
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.BR argv[0] )
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from string variable
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.BR progargs .
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.TP
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.B win()
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Like
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.IR new (),
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but run the process in a separate window.
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.TP
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.BI start( pid )
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Start a stopped process.
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.TP
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.BI kill( pid )
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Kill the given process.
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.TP
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.BI setproc( pid )
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Make the given process current.
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.TP
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.BI rc( string )
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Escape to the shell,
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.MR rc 1 ,
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to execute the command string.
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.TP
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.BI include( string )
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Read acid commands from the named file.
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.TP
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.BI includepipe( string )
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Run the command string, reading its standard output as acid commands.
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.PD 0
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.SS "Shared library segments
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When a pid or core file is specified on the command line,
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.I acid
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will, as part of its startup, determine the set of shared libraries
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in use by the process image and map those at appropriate locations.
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If
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.I acid
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is started without a pid or core file
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and is subsequently attached to a process via
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.BR setproc ,
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the shared library maps can be initialized by calling
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.BR dynamicmap() .
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.SS "Type information
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Unix compilers conventionally include detailed type information
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in the debugging symbol section of binaries.
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The external program
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.B acidtypes
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extracts this information and formats it as
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.I acid
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program text.
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Once the shared libraries have been mapped, the default
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.I acid
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startup invokes
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.B acidtypes
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(via
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.BR includepipe )
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on the set of currently mapped text files.
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The function
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.B acidtypes()
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can be called to rerun the command after changing
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the set of mapped text files.
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.SS "Acid Libraries
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There are a number of
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.I acid
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`libraries' that provide higher-level debugging facilities. One notable
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example is
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.IR trump ,
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which uses
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.I acid
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to trace memory allocation.
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.I Trump
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requires starting
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.I acid
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on the program, either by attaching to a running process or by
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executing
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.B new()
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on a binary (perhaps after setting
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.BR progargs ),
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stopping the process, and then running
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.B trump()
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to execute the program under the scaffolding.
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The output will be a trace of the memory allocation and free calls
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executed by the program.
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When finished tracing, stop the process and execute
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.B untrump()
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followed by
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.B cont()
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to resume execution.
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.SH EXAMPLES
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Start to debug
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.BR /bin/ls ;
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set some breakpoints; run up to the first one
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(this example doesn't work on Unix yet):
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.IP
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.EX
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% acid /bin/ls
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/bin/ls: mips plan 9 executable
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/sys/lib/acid/port
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/sys/lib/acid/mips
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acid: new()
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70094: system call _main ADD $-0x14,R29
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70094: breakpoint main+0x4 MOVW R31,0x0(R29)
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acid: pid
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70094
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acid: argv0 = **main:argv\es
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acid: whatis argv0
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integer variable format s
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acid: *argv0
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/bin/ls
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acid: bpset(ls)
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acid: cont()
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70094: breakpoint ls ADD $-0x16c8,R29
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acid:
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.EE
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.PP
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Display elements of a linked list of structures:
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.IP
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.EX
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complex Str { 'D' 0 val; 'X' 4 next; };
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s = *headstr;
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while s != 0 do{
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complex Str s;
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print(s.val, "\en");
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s = s.next;
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}
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.EE
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.PP
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Note the use of the
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.B .
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operator instead of
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.BR -> .
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.PP
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Display an array of bytes declared in C as
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.BR "char array[]" .
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.IP
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.EX
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*(array\es)
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.EE
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.PP
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This example gives
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.B array
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string format, then prints the string beginning at the address (in
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.I acid
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notation)
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.BR *array .
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.PP
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Trace the system calls executed by
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.MR ls 1
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(neither does this one):
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.IP
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.EX
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% acid -l truss /bin/ls
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/bin/ls:386 plan 9 executable
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/sys/lib/acid/port
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/sys/lib/acid/kernel
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/sys/lib/acid/truss
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/sys/lib/acid/386
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acid: progargs = "-l lib/profile"
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acid: new()
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acid: truss()
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open("#c/pid", 0)
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return value: 3
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pread(3, 0x7fffeeac, 20, -1)
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return value: 12
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data: " 166 "
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\&...
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stat("lib/profile", 0x0000f8cc, 113)
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return value: 65
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open("/env/timezone", 0)
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return value: 3
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pread(3, 0x7fffd7c4, 1680, -1)
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return value: 1518
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data: "EST -18000 EDT -14400
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9943200 25664400 41392800 57718800 73447200 89168400
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104896800 ..."
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close(3)
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return value: 0
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pwrite(1, "--rw-rw-r-- M 9 rob rob 2519 Mar 22 10:29 lib/profile
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", 54, -1)
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--rw-rw-r-- M 9 rob rob 2519 Mar 22 10:29 lib/profile
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return value: 54
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\&...
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166: breakpoint _exits+0x5 INTB $0x40
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acid: cont()
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.EE
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.SH FILES
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.B \*9/acid/$objtype
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.br
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.B \*9/acid/port
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.br
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.B \*9/acid/kernel
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.br
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.B \*9/acid/trump
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.br
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.B \*9/acid/truss
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.br
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.B $HOME/lib/acid
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.SH SOURCE
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.B \*9/src/cmd/acid
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.SH "SEE ALSO"
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.MR mk 1 ,
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.MR db 1
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.br
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Phil Winterbottom,
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``Acid Manual''.
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.SH DIAGNOSTICS
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At termination, kill commands are proposed
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for processes that are still active.
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.SH BUGS
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There is no way to redirect the standard input and standard output
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of a new process.
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.PP
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Source line selection near the beginning of a file may pick
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an adjacent file.
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.PP
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With the extant stepping commands, one cannot step through instructions
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outside the text segment and it is hard to debug across process forks.
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.PP
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Breakpoints do not work yet.
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Therefore, commands such as
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.BR step ,
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.BR new ,
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and
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.B truss
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do not work either.
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.B New
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in particular will need some help to cope with dynamic libraries.
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