5.1 Makefile Overview

A makefile contains a sequence of entries, each of which specifies a build target, some dependencies, and the build scripts of commands to be executed. A makefile can also contain make macro definitions, target-dependent macro definitions, and build directives (special targets.)

• Target/dependencies line. The first line of an entry is a white-space-separated, nonnull list of targets, followed by a colon (:) or a double colon (::), and a (possibly empty) list of dependencies. Both targets and dependencies may contain ClearCase pathname patterns. (See the wildcards_ccase reference page.)

The list of dependencies may not need to include source objects, such as header files, because clearmake detects these dependencies. However, the list must include build-order dependencies, for example, object modules and libraries that must be built before executables. (See Build-Order Dependencies.)

• Build script. Text following a semicolon (;) on the same line, and all subsequent lines that begin with a <TAB> character, constitute a build script: a set of commands to be executed in a command interpreter. A command can be continued onto the next text line with a \<NL> sequence. Any line beginning with a number sign (#) is a comment.

A build script ends at the first nonempty line that does not begin with a <TAB> or number sign (#); this begins a new target/dependencies line or a make macro definition.

Build scripts must use standard pathnames only. Do not include view-extended or version-extended pathnames in a build script.

Executing a build script updates the target, and is called a target rebuild. The commands in a build script are executed one at a time, each in its own instances of the command interpreter.

Note that clearmake always completely eliminates a \<NL> sequence, even in its compatibility modes. Some other make programs sometimes preserve such a sequence.

• Make macro. A make macro is an assignment of a character-string value to a simple name. By convention, all letters in the name are uppercase (for example, CFLAGS).

• Target-dependent macro definitions. A target-dependent macro definition takes the form target-list := macro_name = string

You can use macros in makefiles or in BOS files. For more information, see Target-Dependent Macro Definitions.

• Special targets. A line that begins with a dot (.) is a special target, which acts as a directive to clearmake.

• Special characters in target names. You can use special characters in target names by immediately preceding each special character with a backslash (\).