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LD(1) General Commands Manual LD(1) NAME ld - link editor or loader SYNOPSIS ld [ option ... ] file ... DESCRIPTION Ld combines several object programs into one, resolves external refer- ences, and searches libraries. In the simplest case several object files are given, and ld combines them, producing an object module which can be either executed 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 This file is made executable only if no errors occurred during the load. The argument routines are concatenated in the order specified. The en- try 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 li- brary references another routine 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; see lorder(1). The first member of a library should be a file named __.SYMDEF, which is under- stood to be a dictionary for the library as produced by ranlib; the dictionary is searched iteratively to satisfy as many references as possible. The symbols and and in C) are reserved, and if referred to, are set to the first location above the program, the first location above initial- ized data, and the first location above all data, respectively. It is erroneous to define these symbols. Ld understands several options. Except for -l and -o, they should ap- pear before the file names. -A Load incrementally, so that the resulting object code may be read into an already executing program. The next argument names an object file whose symbol table will be added to. Only newly linked material will be entered into the text and data portions of but the new symbol table will reflect every symbol defined before and after the incremental load. -A must not follow any object file names. -D Take the next argument as a hexadecimal number and pad the data segment with zeros to the indicated length. -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 default. -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 encoun- tered, so the placement of the option 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 that when the output file is executed, the text portion will be read-only and shared among all users executing the file. (Use magic number 0410 and move the data segment to a 1024 byte boundary.) -o The name argument after -o is used as the name of the ld output file, instead of -r Generate relocation bits in the output file so that it can be the subject of another ld run. This flag also prevents final fixing of `common' symbols (uninitialized C variables or Fortran common variables), and suppresses `undefined symbol' diagnos- tics. -s Strip the output, that is, remove the symbol table and reloca- tion bits to save space (but impair the usefulness of the debug- gers). This information can also be removed by strip(1). -S Partially strip; remove all symbols that were not in the source. -T The next argument is a hexadecimal number which sets the text segment origin. With option -A this origin must be a multiple of 1024. The default is 0, or _end with -A. -t (trace) Print the name of each file as it is processed. -u Take the following argument as a symbol and enter it as unde- fined in the symbol table. This is useful for loading wholly from a library, since initially the symbol 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 This option is used by cc(1) to discard internally-generated labels while retaining symbols local to routines. -x Do not preserve local symbols in the output symbol table; only enter external symbols. This option saves some space in the output file. -ysym 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 underscore as external C, Fortran, and Pascal vari- ables begin with underscores.) -z Arrange for the process to be loaded on demand from the result- ing executable file (magic number 413) rather than preloaded. This (default) output format has a 1024-byte header followed by a text and data segment each of which have size a multiple of 1024 bytes (being padded out with zeros if necessary). The first few BSS segment symbols may appear in the data segment to avoid wasting space at the end of that segment. FILES libraries more libraries output file SEE ALSO as(1), ar(1), cc(1), f77(1), size(1), nm(1), lorder(1), a.out(5) BUGS There is no way to force data to be page aligned. LD(1)