You may want to specify executable and core dump file names. The usual way to do this is at start-up time, using the arguments to 's start-up commands (see section Getting In and Out of).
Occasionally it is necessary to change to a different file during a session. Or you may run and forget to specify a file you want to use. In these situations the commands to specify new files are useful.
file filename
run command. If you do not specify a
directory and the file is not found in the working directory,
uses the environment variable PATH as a list of
directories to search, just as the shell does when looking for a program
to run. You can change the value of this variable, for both
and your program, using the path command.
On systems with memory-mapped files, an auxiliary file
`filename.syms' may hold symbol table information for
filename. If so, maps in the symbol table from
`filename.syms', starting up more quickly. See the
descriptions of the file options `-mapped' and `-readnow'
(available on the command line, and with the commands file,
symbol-file, or add-symbol-file, described below),
for more information.
file
file with no argument makes discard any information it
has on both executable file and the symbol table.
exec-file [ filename ]
PATH
if necessary to locate your program. Omitting filename means to
discard information on the executable file.
symbol-file [ filename ]
PATH is
searched when necessary. Use the file command to get both symbol
table and program to run from the same file.
symbol-file with no argument clears out information on your
program's symbol table.
The symbol-file command causes to forget the contents
of its convenience variables, the value history, and all breakpoints and
auto-display expressions. This is because they may contain pointers to
the internal data recording symbols and data types, which are part of
the old symbol table data being discarded inside .
symbol-file does not repeat if you press RET again after
executing it once.
When is configured for a particular environment, it
understands debugging information in whatever format is the standard
generated for that environment; you may use either a GNU compiler, or
other compilers that adhere to the local conventions. Best results are
usually obtained from GNU compilers; for example, using symbol-file command does not
normally read the symbol table in full right away. Instead, it scans
the symbol table quickly to find which source files and which symbols
are present. The details are read later, one source file at a time,
as they are needed.
The purpose of this two-stage reading strategy is to make start up
faster. For the most part, it is invisible except for occasional
pauses while the symbol table details for a particular source file are
being read. (The set verbose command can turn these pauses
into messages if desired. See section Optional warnings and messages.)
We have not implemented the two-stage strategy for COFF yet. When the
symbol table is stored in COFF format, symbol-file reads the
symbol table data in full right away.
symbol-file filename [ -readnow ] [ -mapped ]
file filename [ -readnow ] [ -mapped ]
mmap system call, you can use another option, `-mapped', to
cause to write the symbols for your program into a reusable
file. Future debugging sessions map in symbol information
from this auxiliary symbol file (if the program has not changed), rather
than spending time reading the symbol table from the executable
program. Using the `-mapped' option has the same effect as
starting with the `-mapped' command-line option.
You can use both options together, to make sure the auxiliary symbol
file has all the symbol information for your program.
The auxiliary symbol file for a program called myprog is called
`myprog.syms'. Once this file exists (so long as it is newer
than the corresponding executable), always attempts to use
it when you debug myprog; no special options or commands are
needed.
The `.syms' file is specific to the host machine where you run
. It holds an exact image of the internal
symbol table. It cannot be shared across multiple host platforms.
core-file [ filename ]
core-file with no argument specifies that no core file is
to be used.
Note that the core file is ignored when your program is actually running
under . So, if you have been running your program and you wish to
debug a core file instead, you must kill the subprocess in which the
program is running. To do this, use the kill command
(see section Killing the child process).
load filename
load does not repeat if you press RET again after using it.
add-symbol-file filename address
add-symbol-file filename address [ -readnow ] [ -mapped ]
add-symbol-file command reads additional symbol table information
from the file filename. You would use this command when filename
has been dynamically loaded (by some other means) into the program that
is running. address should be the memory address at which the
file has been loaded; cannot figure this out for itself.
You can specify address as an expression.
The symbol table of the file filename is added to the symbol table
originally read with the symbol-file command. You can use the
add-symbol-file command any number of times; the new symbol data thus
read keeps adding to the old. To discard all old symbol data instead,
use the symbol-file command.
add-symbol-file does not repeat if you press RET after using it.
You can use the `-mapped' and `-readnow' options just as with
the symbol-file command, to change how manages the symbol
table information for filename.
add-shared-symbol-file
add-shared-symbol-file command can be used only under Harris' CXUX
operating system for the Motorola 88k. automatically looks for
shared libraries, however if does not find yours, you can run
add-shared-symbol-file. It takes no arguments.
section
section command changes the base address of section SECTION of
the exec file to ADDR. This can be used if the exec file does not contain
section addresses, (such as in the a.out format), or when the addresses
specified in the file itself are wrong. Each section must be changed
separately. The "info files" command lists all the sections and their
addresses.
info files
info target
info files and info target are synonymous; both print
the current target (see section Specifying a Debugging Target),
including the
names of the executable and core dump files
currently in use by , and the files from which symbols were
loaded. The command help target lists all possible targets
rather than current ones.
All file-specifying commands allow both absolute and relative file names as arguments. always converts the file name to an absolute file name and remembers it that way.
supports SunOS, SVr4, Irix 5, and IBM RS/6000 shared libraries.
automatically loads symbol definitions from shared libraries
when you use the run command, or when you examine a core file.
(Before you issue the run command, does not understand
references to a function in a shared library, however--unless you are
debugging a core file).
info share
info sharedlibrary
sharedlibrary regex
share regex
run. If
regex is omitted all shared libraries required by your program are
loaded.
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