Intel XENIX 286 Programmers Guide (86) - Tenox.tc

CHAPTER 4
make: PROGRAM MAINTAINER
The make program provides an easy way to automate the creation of large programs.
make reads commands from a user-defined "makefile" that lists the files to be created,
the commands that create them, and the files from which they are created. When you
direct make to create a program, it makes sure that each file on which the program
depends is up to date, then creates the program by executing the given commands. If a
file is not up to date, make updates it before creating the program by executing
explicitly given commands or one of the many built-in commands.
This chapter explains how to use make to automate medium-sized programming
projects. It explains how to create makefiles for each project and how to invoke make
for creat ing programs and updating files. For more details about the program, see make
in "Commands" in the XENIX 286 Reference Manual.
Creating a Makefile
A makefile contains one or more lines of text called dependency lines. A dependency
line shows how a given file depends on other files and what commands are required to
bring a file up to date. A dependency line has the form
target ... : [ dependent .. . ] [ ; command ... ]
where target is the name of a file to be updated, dependent is the name of a file on
which the target depends, and command is the XENIX command needed to create the
target file. Each dependency line must have at least one command associated with it,
even if it is only the null command (;).
You may give more than one target name or dependent name if desired. Each name
must be separated from the next by at least one space. The target names must be
separated from the dependent names by a colon (:). File names must be spelled as
defined by the XENIX system. Shell metacharacters, such as star (*) and question mark
(?), in file names are expanded when make uses the name.
You may give a sequence of commands on the same line as the target and dependent
names if you precede each command with a semicolon (;). You can give additional
commands on following lines by beginning each line with a tab character. Commands
must be given exactly as they would appear on a shell command line. The at sign (@)
may be placed in front of a command to prevent make from displaying the command
before executing it. Shell commands, such as cd, must appear on single lines; they must
not contain the backslash (\} and newline character combination that normally can be
used to continue commands between lines.
You may add a comment to a makefile by starting the com ment with a nu mber sign (#)
and ending it with a newline character. All characters after the nu mber sign are
ignored. Comments may be placed at the end of a dependency line if desired. If a
command contains a number sign, it must be enclosed in double quotat ion marks ("#").
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