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Annotation of 43BSDTahoe/new/help/src/f77/debugging, revision 1.1.1.1

1.1       root        1: .TI F77/DEBUGGING "Sep. 4, 1985"
                      2: Debugging Aids for F77 Programs
                      3: 
                      4: The first step in debugging is to understand the error message you
                      5: are getting.  See "help f77 error_msgs" for advice on that.
                      6: 
                      7: There are several utilities that can be used in debugging.
                      8: If you have a core dump, use the debugger, dbx, to look at the core dump.
                      9: If you compiled and loaded with the -g flag, dbx can be used to tell
                     10: the line at which your program failed and to display the values of
                     11: variables.  Dbx can also be used to set break points or single step a
                     12: program and do interactive debugging.
                     13: 
                     14: If you did not compile with the -g flag,
                     15: dbx will still tell you which subroutines were active at the time
                     16: of the failure.  See "help f77 dbx" and "man dbx" for more information.
                     17: 
                     18: If you might be exceeding the bounds of an array,
                     19: you can use f77's -C flag to check for subscripts out of range.
                     20: 
                     21: The 'nm' utility is useful in telling which procedures are referenced
                     22: in which '.o' files.  Thus if the loader issues a message like:
                     23: 
                     24: .nf
                     25:        Undefined:
                     26:        _subr_
                     27: .fi
                     28: 
                     29: and you don't know where subr() is called, the command:
                     30: 
                     31:        nm -og *.o | grep subr
                     32: 
                     33: will tell you which '.o' files in this directory reference subr().
                     34: 
                     35: The -M flag can be used to tell out of which archive or library a '.o'
                     36: file is loaded.

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