16 Makefile Conventions

6 Standard Targets for Users

All GNU programs should have the following targets in their Makefiles:

• all ：Compile the entire program. This should be the default target. This target need not rebuild any documentation files; Info files should normally be included in the distribution, and DVI (and other documentation format) files should be made only when explicitly asked for.
  By default, the Make rules should compile and link with ‘-g’, so that executable programs have debugging symbols. Otherwise, you are essentially helpless in the face of a crash, and it is often far from easy to reproduce with a fresh build.
• install ：Compile the program and copy the executables, libraries, and so on to the file names where they should reside for actual use. If there is a simple test to verify that a program is properly installed, this target should run that test.
  Do not strip executables when installing them. This helps eventual debugging that may be needed later, and nowadays disk space is cheap and dynamic loaders typically ensure debug sections are not loaded during normal execution. Users that need stripped binaries may invoke the install-strip target to do that.
  If possible, write the install target rule so that it does not modify anything in the directory where the program was built, provided ‘make all’ has just been done. This is convenient for building the program under one user name and installing it under another.
  The commands should create all the directories in which files are to be installed, if they don’t already exist. This includes the directories specified as the values of the variables prefix and exec_prefix, as well as all subdirectories that are needed. One way to do this is by means of an installdirs target as described below.
  Use ‘-’ before any command for installing a man page, so that make will ignore any errors. This is in case there are systems that don’t have the Unix man page documentation system installed.
  The way to install Info files is to copy them into $(infodir) with $(INSTALL_DATA) (see Command Variables), and then run the install-info program if it is present. install-info is a program that edits the Info dir file to add or update the menu entry for the given Info file; it is part of the Texinfo package.
  Here is a sample rule to install an Info file that also tries to handle some additional situations, such as install-info not being present.

do-install-info: foo.info installdirs
        $(NORMAL_INSTALL)
# Prefer an info file in . to one in srcdir.
        if test -f foo.info; then d=.; \
         else d="$(srcdir)"; fi; \
        $(INSTALL_DATA) $$d/foo.info \
          "$(DESTDIR)$(infodir)/foo.info"
# Run install-info only if it exists.
# Use 'if' instead of just prepending '-' to the
# line so we notice real errors from install-info.
# Use '$(SHELL) -c' because some shells do not
# fail gracefully when there is an unknown command.
        $(POST_INSTALL)
        if $(SHELL) -c 'install-info --version' \
           >/dev/null 2>&1; then \
          install-info --dir-file="$(DESTDIR)$(infodir)/dir" \
                       "$(DESTDIR)$(infodir)/foo.info"; \
        else true; fi

When writing the install target, you must classify all the commands into three categories: normal ones, pre-installation commands and post-installation commands. See Install Command Categories.