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(libtool.info)Debugging executables

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Debugging executables
=====================

   If `hell' was a complicated program, you would certainly want to
test and debug it before installing it on your system.  In the above
section, you saw how the libtool wrapper script makes it possible to run
the program directly, but unfortunately, this mechanism interferes with
the debugger:

     burger$ gdb hell
     GDB is free software and you are welcome to distribute copies of it
      under certain conditions; type "show copying" to see the conditions.
     There is no warranty for GDB; type "show warranty" for details.
     GDB 4.16 (i386-unknown-netbsd), (C) 1996 Free Software Foundation, Inc.
     
     "hell": not in executable format: File format not recognized
     
     (gdb) quit
     burger$

   Sad.  It doesn't work because GDB doesn't know where the executable
lives.  So, let's try again, by invoking GDB directly on the executable:

     burger$ gdb .libs/hell
     trick:/home/src/libtool/demo$ gdb .libs/hell
     GDB is free software and you are welcome to distribute copies of it
      under certain conditions; type "show copying" to see the conditions.
     There is no warranty for GDB; type "show warranty" for details.
     GDB 4.16 (i386-unknown-netbsd), (C) 1996 Free Software Foundation, Inc.
     (gdb) break main
     Breakpoint 1 at 0x8048547: file main.c, line 29.
     (gdb) run
     Starting program: /home/src/libtool/demo/.libs/hell
     /home/src/libtool/demo/.libs/hell: can't load library 'libhello.so.2'
     
     Program exited with code 020.
     (gdb) quit
     burger$

   Argh.  Now GDB complains because it cannot find the shared library
that `hell' is linked against.  So, we must use libtool in order to
properly set the library path and run the debugger.  Fortunately, we can
forget all about the `.libs' directory, and just run it on the
executable wrapper (Note: Execute mode):

     burger$ libtool gdb hell
     GDB is free software and you are welcome to distribute copies of it
      under certain conditions; type "show copying" to see the conditions.
     There is no warranty for GDB; type "show warranty" for details.
     GDB 4.16 (i386-unknown-netbsd), (C) 1996 Free Software Foundation, Inc.
     (gdb) break main
     Breakpoint 1 at 0x8048547: file main.c, line 29.
     (gdb) run
     Starting program: /home/src/libtool/demo/.libs/hell
     
     Breakpoint 1, main (argc=1, argv=0xbffffc40) at main.c:29
     29	  printf ("Welcome to GNU Hell!\n");
     (gdb) quit
     The program is running.  Quit anyway (and kill it)? (y or n) y
     burger$