Tags And Attributes (HTML & XHTML: The Definitive Guide, 4th Edition)

Every GNU package should have Info files, so every program needs ‘infodir’, but not all need ‘libdir’ or ‘lispdir’. Most compilers other than GCC do not look for header files in directory /usr/local/include. So installing the header files this way is only useful with GCC. Sometimes this is not a problem because some libraries are only really intended to work with GCC. But some libraries are intended to work with other compilers. They should install their header files in two places, one specified by includedir and one specified by oldincludedir. ’ header files for use with compilers other than GCC. This should normally be /usr/include. The Makefile commands should check whether the value of oldincludedir is empty. If it is, they should not try to use it; they should cancel the second installation of the header files. A package should not replace an existing header in this directory unless the header came from the same package.
The importance of this comes when the variable’s old value contains variable references. The first line defines the CFLAGS variable with a reference to another variable, includes. O’ is not expanded when make processes the definition of CFLAGS. Thus, includes need not be defined yet for its value to take effect. It only has to be defined before any reference to CFLAGS. This is pretty close, but not quite what we want. ’ before setting the variable. If includes is not yet defined, we get ‘ -O -pg’, and a later definition of includes will have no effect. ’ still uses its value. If a variable has been set with a command argument (see Overriding Variables), then ordinary assignments in the makefile are ignored. See Appending More Text to Variables. Variable assignments marked with the override flag have a higher priority than all other assignments, except another override. Subsequent assignments or appends to this variable which are not marked override will be ignored.
If the install or uninstall target has any dependencies which act as subroutines of installation, then you should start each dependency’s commands with a category line, and start the main target’s commands with a category line also. This way, you can ensure that each command is placed in the right category regardless of which of the dependencies actually run. The reason for distinguishing the commands in this way is for the sake of making binary packages. Typically a binary package contains all the executables and other files that need to be installed, and has its own method of installing them-so it does not need to run the normal installation commands. But installing the binary package does need to execute the pre-installation and post-installation commands. Programs to build binary packages work by extracting the pre-installation and post-installation commands. This appendix summarizes the directives, text manipulation functions, and special variables which GNU make understands. See Special Built-in Target Names, Catalogue of Built-In Rules, and Summary of Options, for other summaries.
Please make these install-format targets invoke the commands for the format target, for example, by making format a dependency. This rule should not modify the directories where compilation is done, only the directories where files are installed. The uninstallation commands are divided into three categories, just like the installation commands. See Install Command Categories. Like install, but strip the executable files while installing them. But if the package installs scripts as well as real executables, the install-strip target can’t just refer to the install target; it has to strip the executables but not the scripts. It should only strip the copies that are installed. Normally we do not recommend stripping an executable unless you are sure the program has no bugs. However, it can be reasonable to install a stripped executable for actual execution while saving the unstripped executable elsewhere in case there is a bug. Delete all files in the current directory that are normally created by building the program.
See Variables from the Environment. Several automatic variables are given new values for each rule. Each of these has a single conventional use. Several variables have constant initial values. See Variables Used by Implicit Rules. ’. Whatever follows the operator and any initial whitespace on the line becomes the value. ‘main.o foo.o bar.o utils.o’. ’ are recursively expanded variables. ’ are simply expanded variables; these definitions can contain variable references which will be expanded before the definition is made. ’ are immediately expanded variables. The different assignment operators are described in See The Two Flavors of Variables. The variable name may contain function and variable references, which are expanded when the line is read to find the actual variable name to use. There is no limit on the length of the value of a variable except the amount of memory on the computer. You can split the value of a variable into multiple physical lines for readability (see Splitting Long Lines).
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