Appendix C. Predefined dbx Variables

Predefined dbx variables are listed in the following table. The predefined variable names begin with “$” so that they do not conflict with variable, command, or alias names.

Table C-1. Predefined dbx Variables






Specifies the format for addresses. This can be set to any format valid for the C language printf(3S) function.



Specifies the format for 64-bit addresses. This can be set to any format valid for the C language printf(3S) function.



If nonzero, the new value of a program variable will be displayed after the assign command.



If 0, symbol names are case sensitive. If 1, symbol names are not case sensitive. If 2, the case sensitivity of symbol names depends on the case sensitivity of the language in which the symbol was defined.



If 1, the words unsigned, short, long, int, char, struct, union, and enum are keywords usable only in type casts. If 0, struct , union, and enum are ordinary words with no predefined meaning (in C modules, the others are still known as C types).



The last event number as seen by the status command.



The current line in the source code being executed.



The current program counter.



The current source listing line plus one.



The name of the file that dbx uses when the record input or the playback input command is executed with no argument.



The name of the file that dbx uses when the record output or the playback output command is executed with no argument.



The name of the editor to invoke (with the edit command). Default value is set to the value of the EDITOR environment variable. If EDITOR missing, it defaults to vi.



When nonzero, dbx runs programs on R8000 processors in floating point precise mode, allowing accurate floating point exceptions. By default, R8000 floating point interrupts are asynchronous and reported program counter values are useless for debugging. For more information about floating point precise mode, see the syssgi(2) reference page section on SGI_SET_FP_PRECISE .



If 1, all references to registers are to the registers of the current activation level. If 0, all references are to the hardware registers.



If 0, adds only processes created with the sproc(2) system call to the process group list automatically. If 1, then adds processes created with either the fork(2) or sproc system calls to process group list.



If nonzero, outputs characters in hexadecimal, using C format %x. This affects char type variables, including those in structures. It does not affect arrays of characters, which are printed using the %.*s format.



If nonzero, displays floating point and double-precision variables both as literals and as hexadecimal representations of the bit pattern.



If nonzero, input constants are assumed to be in hexadecimal. This overrides $octin.



If nonzero, outputs integers in hexadecimal format. This overrides $octints.



If nonzero, outputs strings and arrays in hexadecimal. For character arrays, if nonzero, the null byte is not taken as a terminator. Instead, prints the entire array (or $maxlen values, whichever is less). If 0, then a null byte in a C or C++ character array is taken as the end of the array (the length of the array and $maxstrlen can terminate the array printing before a null byte is found).



The current history line number.



The process ID of the last child process created by a fork or sproc system call.



The number of lines in the history list.



Specifies how many lines the list command lists.



Maximum length printed for zero-terminated char strings and arrays. Prints char arrays for array-length, $maxstrlen bytes, or up to a null byte, whichever comes first (see $hexstrings).



If 0, treats calls to sproc in the same way as it treats calls to fork. If 1, child processes created by calls to sproc are allowed to run; they block on multiprocessor synchronization code emitted by mp Fortran code. When you set $mp_program to 1, mp Fortran code is easier to debug.



After every command creating an event, this variable is set to the event's number. The $newevent variable is useful in writing scripts that do not use hard-coded event numbers.



Stores the number of the latest pgrp event created by stop[i], trace[i] , and when[i]... pgrp. Useful when writing scripts .



Only used with addproc or with dbx options -p and -P. If 0, the process that is the argument of the command is stopped; if 1, the process is not stopped. In either case the process state is not changed. If the you start dbx with the - N option, then $nonstop should1.



If nonzero, assumes input constants are in octal.

$hexin overrides $octin.



If nonzero, outputs integers in octal format.

$hexints takes precedence.



Specifies whether to page when dbx output scrolls information off the current screen. A nonzero value turns on paging; a 0 value turns it off.



The name of the program used to display output from dbx.



The width of the window in characters (assumes a fixed-width font). Used by dbx to calculate how many screen lines are output. dbx never inserts newlines; the window software wraps the lines.



Specifies how many lines print when information is longer than one screen. This can be changed to match the number of lines on any terminal. If set to 0, 1 is used.



If nonzero, allows traps that cannot be satisfied immediately to wait until they can be satisfied. This is useful for debugging programs that use DSOs, as it allows setting breakpoints before the dlopen() call. When set to nonzero, mistyped procedure names are not flagged and cause a pending trap to be set.



If 1, adds commands read from files using the playback input command to the command history. If 0, does not add the commands to the history.



The current process for kernel debugging (-k).



Set by dbx to the process ID of the running process (also called the object file).



If 1, prints the commands read from files using the playback input command. If 0, does not print the commands. In either case, dbx prints the output resulting from such commands.



Used when disassembling. If 1, prints register contents alongside disassembled instructions. If 0, just prints disassembled instructions.



If nonzero, the display of a kernel exception frame by the dump or where commands includes information that you can use to find the contents of the kernel registers at the time of the fault.



If 0, prints only the next line to be executed. If nonzero, prints each line that is executed while it single steps.



If 0, prints arrays, unions, structures and classes one element per line. If nonzero, prints arrays compactly (wide).



This variable applies only if you invoke dbx with the -k option (that is, it is not available unless you are doing kernel debugging). Whenever $pid is set, dbx sets $procaddr to the address of the process table entry for that process.



The prompt for dbx.



If 0, does not add the child process to the process pool. Both the child process and the parent process continue to run.

If 1, stops the parent process and asks if you want to add the child process to the process pool. If you answer yes, adds the child process to the pool and stops the child process; if you answer no, allows the child process to run and does not place it in the process pool.

If 2, dbx automatically stops both the parent and child processes and adds the child process to the process pool.



If 0, uses the alternate form of the register name (for example, zero instead of r0 and t1 instead of r9). If nonzero, uses the machine name (r0 through r31).



If nonzero, entering a null line (entering a newline on an empty line) repeats the last command. If 0, performs no action.



If 1, records commands you enter in addition to output when using the record output command. If 0, does not copy the commands.


“ “

A string that is added by run to the command line it passes to the command interpreter. Use $shellparameters to disable spawning of subshells by the initialization file of a non-standard shell.



If nonzero, shows the address of each breakpoint placed in the code each time it is placed. Removal of the breakpoints is not shown. If multiple breakpoints are placed at one location, only one of the placements is shown. Since breakpoints are frequently placed and removed by dbx, the volume of output can be annoying when tracing.



If 0, step, next, and so on do not show the source file name in the dbx message describing the stopped state.

If 1, prints just the base file name.

If 2, prints the full path.

If $stopformat is 1, $showfilename equals 0 is treated as if $ showfilename were 2.



If 0, search for a source file by:

a) using the pathname in the object file's debugging information;

if the file is not found, then

b) examine pathnames remapped by the dir or use command;

if the file is still not found, then

c) reduce full pathnames to base file names and search the list of directories created by the dir or use command.

If 1, permute the default source-file search sequence to: step b, step c, then step a.

If 2, use only steps b and c of the default source-file search sequence.



Sets the maximum number of frames that will be examined by the dump, func, and where commands.



If nonzero, attempts in dbx expressions to model exactly the promotion rules of ANSI C and ISO/IEC 9899 C (even to the point of matching float to float rather than converting all floating points to doubles).

If 0, promotes variables more like traditional pcc C (but promotions of 16-bit and 8-bit unsigned is to int, not unsigned int).



If 0, step steps into all procedures that are compiled with debugging options -g -g2, or -g3 for which line numbers are available in the symbol table. Note that standard library routines are excluded.

If 1, in addition to the procedures above, steps into any procedures for which a source file can be found. Note that when you debug a source file compiled without symbols or compiled with optimization, the line numbers may jump erratically.

If 2, steps into all procedures. Note that if dbx cannot locate a source file, then it cannot display source lines as you step through a procedure.



If 0, stopping messages appear in the traditional IRIX dbx format, for example:

stopped at [main:32 , 0x400000 main.c]If 1, messages appear in a more standard BSD dbx format:

stopped in main at line 32 in file “main.c”See affect on $showfilename also.



The name of a file of tags, as created by ctags(1). Used by the tag command.



If 1, whereis looks only in main object.

If 0, whereis checks all objects.

If n, whereis checks first n objects.