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5.6 Options for Debugging Your Program or GNU Fortran

GNU Fortran has various special options that are used for debugging either your program or g77

-g
Produce debugging information in the operating system's native format (stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging information.

A sample debugging session looks like this (note the use of the breakpoint):

          $ cat gdb.f
                PROGRAM PROG
                DIMENSION A(10)
                DATA A /1.,2.,3.,4.,5.,6.,7.,8.,9.,10./
                A(5) = 4.
                PRINT*,A
                END
          $ g77 -g -O gdb.f
          $ gdb a.out
          ...
          (gdb) break MAIN__
          Breakpoint 1 at 0x8048e96: file gdb.f, line 4.
          (gdb) run
          Starting program: /home/toon/g77-bugs/./a.out
          Breakpoint 1, MAIN__ () at gdb.f:4
          4             A(5) = 4.
          Current language:  auto; currently fortran
          (gdb) print a(5)
          $1 = 5
          (gdb) step
          5             PRINT*,A
          (gdb) print a(5)
          $2 = 4
          ...
     

One could also add the setting of the breakpoint and the first run command to the file .gdbinit in the current directory, to simplify the debugging session.

See Options for Debugging Your Program or GCC (Using the GNU Compiler Collection (GCC)), for more information on debugging options.