Linker and Libraries Guide

Appendix A Link-Editor Quick Reference

The following sections provide a simple overview, or cheat sheet, of the most commonly used link-editor scenarios. See Link-Editing for an introduction to the kinds of output modules generated by the link-editor.

The examples provided show the link-editor options as supplied to a compiler driver, this being the most common mechanism of invoking the link-editor. In these examples cc(1) is used. See Using a Compiler Driver.

The link-editor places no meaning on the name of any input file. Each file is opened and inspected to determine the type of processing it requires. See Input File Processing.

Shared objects that follow a naming convention of, and archive libraries that follow a naming convention of libx.a, can be input using the -l option. See Library Naming Conventions. This provides additional flexibility in allowing search paths to be specified using the -L option. See Directories Searched by the Link-Editor.

Over time, the link-editor has added many features that provide for the creation of high quality objects. These features can enable the object to be used efficiently and reliably in various runtime environments. However, to ensure backward compatibility with existing build environments, many of these features are not enabled by default. For example, features such as direct bindings and lazy loading must be explicitly enabled. The link-editor provides the -z guidance option to help simplify the process of selecting which features to apply. When guidance is requested, the link-editor can issue warning guidance messages. These messages suggesting options to use, and other related changes, that can help produce higher quality objects. Guidance messages might change over time, as new features are added to the link-editor, or as better practices are discovered to generate high qualify objects. See ld(1).

The link-editor basically operates in one of two modes, static or dynamic.

Static Mode

Static mode is selected when the -d n option is used, and enables you to create relocatable objects and static executables. Under this mode, only relocatable objects and archive libraries are acceptable forms of input. Use of the -l option results in a search for archive libraries.

Creating a Relocatable Object

To create a relocatable object use the -r option.

$ ld -r -o temp.o file1.o file2.o file3.o .....

Creating a Static Executable

Note –

The use of static executables is limited. See Static Executables. Static executables usually contain platform-specific implementation details that restrict the ability of the executable to be run on an alternative platform, or version of the operating system. Many implementations of Oracle Solaris shared objects depend on dynamic linking facilities, such as dlopen(3C) and dlsym(3C). See Loading Additional Objects. These facilities are not available to static executables.

To create a static executable use the -d n option without the -r option.

$ cc -dn -o prog file1.o file2.o file3.o .....

The -a option is available to indicate the creation of a static executable. The use of -d n without a -r implies -a.

Dynamic Mode

Dynamic mode is the default mode of operation for the link-editor. It can be enforced by specifying the -d y option, but is implied when not using the -d n option.

Under this mode, relocatable objects, shared objects and archive libraries are acceptable forms of input. Use of the -l option results in a directory search, where each directory is searched for a shared object. If no shared object is found, the same directory is then searched for an archive library. A search only for archive libraries can be enforced by using the -B static option. See Linking With a Mix of Shared Objects and Archives.

Creating a Shared Object

The following example combines the above points.

$ cc -c -o foo.o -K pic -xregs=no%appl foo.c
$ cc -M mapfile -G -o -z text -z defs -B direct -z lazyload \
-z ignore -R /home/lib foo.o -L. -lbar -lc

The following example combines the above points.

$ cc -M mapfile -G -o -z text -z defs -B direct -z lazyload \
-z ignore -R /home/lib -h foo.o -L. -lbar -lc
$ ln -s

Creating a Dynamic Executable

The following example combines the above points.

$ cc -o prog -R /home/lib -z ignore -z lazyload -B direct -L. \
-lfoo file1.o file2.o file3.o .....