man(1) Manual page archive

     LD(1)                                                       LD(1)

          ld - link editor

          ld [ option ] ... file ...

          Ld combines several object programs into one, resolves
          external references, and searches libraries.  In the sim-
          plest case several object files are given, and ld combines
          them, producing an object module which can be either exe-
          cuted or become the input for a further ld run.  (In the
          latter case, the -r option must be given to preserve the
          relocation bits.)  The output of ld is left on a.out.  This
          file is made executable only if no errors occurred during
          the load.

          The argument routines are concatenated in the order speci-
          fied.  The entry point of the output is the beginning of the
          first routine (unless the -e option is specified).

          If any argument is a library, it is searched exactly once at
          the point it is encountered in the argument list.  Only
          those routines defining an unresolved external reference are
          loaded.  If a routine from a library references another rou-
          tine in the library, and the library has not been processed
          by ranlib (see ar(1)), the referenced routine must appear
          after the referencing routine in the library.  Thus the
          order of programs within libraries may be important.  The
          first member of a library should be a file named `__.SYM-
          DEF', which is understood to be a dictionary for the library
          as produced by ranlib(1); the dictionary is searched itera-
          tively to satisfy as many references as possible.

          The symbols `_etext', `_edata' and `_end' (`etext', `edata'
          and `end' in C) are reserved, and if referred to, are set to
          the first location above the program, the first location
          above initialized data, and the first location above all
          data respectively.  It is erroneous to define these symbols.

          Ld understands several options.  Except for -l, they should
          appear before the file names.

          -A   This option specifies incremental loading, i.e.  link-
               ing is to be done in a manner so that the resulting
               object may be read into an already executing program.
               The next argument is the name of a file whose symbol
               table will be taken as a basis on which to define addi-
               tional symbols.  Only newly linked material will be
               entered into the text and data portions of a.out, but

     LD(1)                                                       LD(1)

               the new symbol table will reflect every symbol defined
               before and after the incremental load.  This argument
               must appear before any other object file in the argu-
               ment list.  The -T option may be used as well, and will
               be taken to mean that the newly linked segment will
               commence at the corresponding address (which must be a
               multiple of 1024).  The default value is the old value
               of _end.

          -D   Take the next argument as a hexadecimal number and pad
               the data segment with zero bytes to the indicated

          -d   Force definition of common storage even if the -r flag
               is present.

          -e   The following argument is taken to be the name of the
               entry point of the loaded program; location 0 is the

          -lx  This option is an abbreviation for the library name
               `/lib/libx.a', where x is a string.  If that does not
               exist, ld tries `/usr/lib/libx.a' A library is searched
               when its name is encountered, so the placement of a -l
               is significant.

          -M   produce a primitive load map, listing the names of the
               files which will be loaded.

          -N   Do not make the text portion read only or sharable.
               (Use "magic number" 0407.)

          -n   Arrange (by giving the output file a 0410 "magic num-
               ber") that when the output file is executed, the text
               portion will be read-only and shared among all users
               executing the file.  This involves moving the data
               areas up to the first possible 1024 byte boundary fol-
               lowing the end of the text.

          -o   The name argument after -o is used as the name of the
               ld output file, instead of a.out.

          -r   Generate relocation bits in the output file so that it
               can be the subject of another ld run.  This flag also
               prevents final definitions from being given to common
               symbols, and suppresses the `undefined symbol' diagnos-

          -S   `Strip' the output by removing all symbols except
               locals and globals.

          -s   `Strip' the output, that is, remove the symbol table

     LD(1)                                                       LD(1)

               and relocation bits to save space (but impair the use-
               fulness of the debuggers).  This information can also
               be removed by strip(1).

          -T   The next argument is a hexadecimal number which sets
               the text segment origin.  The default origin is 0.

          -t   (`trace')  Print the name of each file as it is pro-

          -u   Take the following argument as a symbol and enter it as
               undefined in the symbol table.  This is useful for
               loading wholly from a library, since initially the sym-
               bol table is empty and an unresolved reference is
               needed to force the loading of the first routine.

          -X   Save local symbols except for those whose names begin
               with `L'.  This option is used by cc(1) to discard
               internally-generated labels while retaining symbols
               local to routines.

          -x   Do not preserve local (non-.globl) symbols in the out-
               put symbol table; only enter external symbols.  This
               option saves some space in the output file.

               Indicate each file in which sym appears, its type and
               whether the file defines or references it.  Many such
               options may be given to trace many symbols.  (It is
               usually necessary to begin sym with an `_', as external
               C, FORTRAN and Pascal variables begin with under-

          -z   Arrange for the process to be loaded on demand from the
               resulting executable file (413 format) rather than
               preloaded.  This is the default.  Results in a 1024
               byte header on the output file followed by a text and
               data segment each of which have size a multiple of 1024
               bytes (being padded out with nulls in the file if nec-
               essary).  With this format the first few BSS segment
               symbols may actually appear (from the output of
               size(1)) to live in the data segment; this to avoid
               wasting the space resulting from data segment size

          /lib/lib*.a            libraries
          /usr/lib/lib*.a        more libraries
          /usr/local/lib/lib*.a  still more libraries
          a.out                  output file


     LD(1)                                                       LD(1)

          as(1), ar(1), cc(1), ranlib(1), size(1), nm(1)

          There is no way to force data to be page aligned.