11/3/71                                                    LD (I)

NAME            ld  --  link editor

SYNOPSIS        ld [ -usaol ] name  ]

DESCRIPTION     ld  combines several object programs into one;

                resolves external references; and searches li-

                braries.  In the simplest case the names of sev-

                eral object programs are given, and ld combines

                them, producing an object module which can be ei-

                ther executed or become the input for a further

                ld run.

                The argument routines are concatenated in the or-

                der specified.  The entry point of the output is

                the beginning of the first routine.

                If any argument is a library, it is searched, and

                only those routines defining an unresolved exter-

                nal reference are loaded.  If any routine loaded

                from a library refers to an undefined symbol

                which does not become defined by the end of the

                library, the library is searched again.  Thus the

                order of libraries primarily affects the effi-

                ciency of loading, not what routines get loaded.

                ld understands several flag arguments which are

                written preceded by a "-":

                   -s "squash" the output, that is, remove the

                      symbol table and relocation bits to save

                      space (but impair the usefulness of the de-

                      bugger).  This information can also be re-

                      moved by strip.

                   -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 symbol table

                      is empty and an unresolved reference is

                      needed to force the loading of the first


                   -o set the origin of the load to the octal

                      number which is given as the next argument.

                      This option affects only the definition of

                      relocatable external symbols. See DMR be-

                      fore using.

                   -l This option is an abbreviation for a li-

                      brary name.  "-l" alone stands for

                      "/etc/liba.a", which is the standard system

                      library for assembly language programs.

                      "-lx" stands for "/etc/libx.a" where x is

                      any character.  There are libraries for

                      Fortran (x="f") and B (x="b").

                   -a means "absolute" (load at origin absolute

                      0) but it doesn't work.

                The output of ld is left on a.out.  This file is

                executable only if no errors occurred during the


FILES           /etc/libx.a, for various x;

                /etc/ltma, ltmb, ... (temporary)

                a.out (output file)

SEE ALSO        as, strip, ar (maintains libraries)

DIAGNOSTICS     "can't create temp file"-- unwritable directory

                or someone else is using ld in the same direc-


                "can't open temp file"-- maybe someone has delet-

                ed it out from under you.

                "file not found"-- bad argument

                "bad format"-- bad argument

                "relocation error"-- bad argument (relocation

                bits corrupted)

                "bad relocation"-- user error:  a relocatable

                reference to an external symbol that turns out to

                be absolute.

                "multiply defined"-- same symbol defined twice in

                same load

                "un"-- stands for "undefined symbol"

                "symbol not found"--  loader bug

BUGS            Option "-a" doesn't work at all; option "-o"

                doesn't work right.

OWNER           dmr