Make Utility

Table of Contents
Usage

vmake [-f makefile] [-dDinrst] [-p<0|1|2>] [target...] [macro=value ...]


Description

vmake takes a file of dependencies (a 'makefile') and decides what commands have to be executed to bring the files up to date. These commands are either executed directly from vmake or written to the standard output without executing them.

If no makefile is specified with a -f option, vmake reads a file named 'makefile', if it exists.

If no target is specified on the command line, vmake uses the first target defined in the first makefile.

vmake mostly conforms to the ANSI C standard.


Options
   -f makefile
Use the description file 'makefile'. '-' as the makefile argument denotes the standard input.


   -d
Display the reasons why vmake chooses to rebuild a target. All dependencies which are newer are displayed.


   -dd
Display the dependency checks in more detail. Dependencies which are older are displayed, as well as newer.


   -D
Display the text of the makefiles that are read from standard input.


   -DD
Display the text of the makefiles and 'default.mk'.


   -e
Let environment variables override macro definitions from makefiles. Normally, makefile macros override environment variables. Command line macro definitions always override both environment variables and makefile macros definitions.


   -i
Ignore error codes returned by commands. This is equivalent to the special target .IGNORE:


   -n
No execution mode. Print commands, but do not execute them. However, if a command line is an invocation of vmake , that line is always executed.


   -r
Do not read in the default file 'default.mk'.


   -s
Silent mode. Do not print command lines before executing them. This is equivalent to the special target .SILENT:.


   -t
Touch the target files, bringing them up to date, rather than performing the rules to reconstruct them.


   -p<0|1|2>
Pause after execution; 0 – never (the default), 1 – after an error, 2 – always.


   macro=value
Macro definition. This definition remains fixed for the vmake invocation. It overrides any regular definitions for the specified macro within the makefiles and from the environment. It is inherited by subordinate MAKE's but act as an environment variable for these. That is, depending on the -e setting, it may be overridden by a makefile definition.

How it works

Makefiles
The first makefile read is 'default.mk', which can be located any-where along the PATH. It typically contains predefined macros and implicit rules. The default name of the makefile is 'makefile' in the current directory. An alternate makefile can be specified using one or more '-f' options on the command line. Multiple '-f's act as the concatenation of all the makefiles in a left-to-right order. The makefile(s) may contain a mixture of comment lines, macro definitions, include lines, and target lines. Lines may be continued across input lines by escaping the NEWLINE with a backslash (\). Anything after a "#" is considered to be a comment, and is stripped from the line. Completely blank lines are ignored. An include line is used to include the text of another makefile. It consists of the word "include" left justified, followed by spaces, and followed by the name of the file that is to be included at this line. Include files may be nested.

Macros
Macros have the form 'WORD = text and more text'. The WORD need not be uppercase, but this is an accepted standard. Later lines which contain $(WORD) or ${WORD} will have this replaced by 'text and more text'. If the macro name is a single character, the parentheses are optional. Note that the expansion is done recursively, so the body of a macro may contain other macro invocations.
 e.g.
  FLINTSTONES = wilma and fred
  RUBBLES = barney and betty
  BEDROCK = $(FLINTSTONES) and $(RUBBLES)
  '$(BEDROCK)' becomes 'wilma and fred and barney and betty'

Also note that whitespace around the equal sign is not relevant when defining a macro. The following four macro definitions are all equivalent:

  MACRO = body
  MACRO= body
  MACRO =body
  MACRO=body

Macros may be added to by using the '+=' notation. Thus

  FLINTSTONES += pebbles and dino

would be (given the examples above) the same as

  FLINTSTONES = wilma and fred and pebbles and dino

Special Macros
   MAKE
This normally has the value "vmake". Any line which invokes MAKE temporarily overrides the -n option, just for the duration of that one line. This allows nested invocations of MAKE to be tested with the -n option.


   MAKEFLAGS
This macro has the set of options provided to vmake as its value. If this is set as an environment variable, the set of options is processed before any command line options. This macro may be explicitly passed to nested vmakes, but it is also available to these invocations as an environment variable.


   SUFFIXES
This contains the default list of suffixes supplied to the special target .SUFFIXES:. It is not sufficient to simply change this macro in order to change the .SUFFIXES: list. That target must be specified in your makefile.

There are several dynamically maintained macros that are useful as abbreviations within rules. It is best not to define them explicitly.

$* - The basename of the current target.

$< - The name of the current dependency file.

$@ - The name of the current target.

The $< and $* macros are normally used for implicit rules. They may be unreliable when used within explicit target command lines.
Targets
A target entry in the makefile has the following format:
  target ... : [dependency ...]
          [rule]/
            ...
Any line that does not have leading whitespace (other than macro definitions) is a 'target' line. Target lines consist of one or more filenames (or macros which expand into same) called targets, followed by a semi-colon (:). The ':' is followed by a list of dependent files.

Special allowance is made on MSDOS for the colons that are needed to specify files on other drives. For example, the following will work as intended:
         c:foo.bar : a:fee.ber

If a target is named in more than one target line, the dependencies and rules are added to form the target's complete dependency list and rule list.The dependents are ones from which a target is constructed. They in turn may be targets of other dependents. In general, for a particular target file, each of its dependent files is 'made', to make sure that each is up to date with respect to it's dependents.

The modification time of the target is compared to the modification times of each dependent file. If the target is older, one or more of the dependents have changed, so the target must be constructed. Of course, this checking is done recursively, so that all dependents of dependents of dependents of ... are up to date.

To reconstruct a target, vmake expands macros, strips off initial whitespace, and either executes the rules directly, or passes each to a shell or COMMAND.COM for execution. For target lines, macros are expanded on input. All other lines have macro expansion delayed until absolutely required.

Special Targets
   .DEFAULT:
The rule for this target is used to process a target when there is no other entry for it, and no implicit rule for building it. vmake ignores all dependencies for this target.


   .DONE:
This target and its dependencies are processed after all other targets are built.


   .IGNORE:
Non-zero error codes returned from commands are ignored. Encountering this in a makefile is the same as specifying -i on the command line.


   .INIT:
This target and its dependencies are processed before any other targets are processed.


   .SILENT:
Commands are not echoed before executing them. Encountering this in a makefile is the same as specifying -s on the command line.


   .SUFFIXES:
The suffixes list for selecting implicit rules. Specifying this target with dependents adds these to the end of the suffixes list. Specifying it with no dependents clears the list. In order to add your own dependents to the head of the list, you could enter:
.SUFFIXES:
.SUFFIXES: .abc $(SUFFIXES)
Rules
A line in a makefile that starts with a TAB or SPACE is a shell line or rule. This line is associated with the most recently preceding dependency line. A sequence of these may be associated with a single dependency line. When a target is out of date with respect to a dependent, the sequence of commands is executed. Shell lines may have any combination of the following characters to the left of the command:

 @  will not echo the command line.
 -   vmake will ignore the exit code of the command, i.e. the ERRORLEVEL of MSDOS. Without this, vmake terminates when a nonzero exit code is returned.
 +  vmake will use COMMAND.COM to execute the command.

If the '+' is not attached to a shell line, but the command is a DOS command or if redirection is used (<, |, >), the shell line is passed to COMMAND.COM anyway.

Implicit Rules
Implicit rules are intimately tied to the .SUFFIXES: special target. Each entry in the .SUFFIXES defines an extension to a filename which may be used to build another file. The implicit rules then define how to actually build one file from another. These files are related, in that they must share a common basename, but have different extensions.

If a file that is being made does not have an explicit target line, an implicit rule is looked for. Each entry in the .SUFFIXES: list is combined with the extension of the target, to get the name of an implicit target. If this target exists, it gives the rules used to transform a file with the dependent extension to the target file. Any dependents of the implicit target are ignored.

In the following example, the .SUFFIXES: list is .c .y .l, and the target file is fred.o which does not have a target line. An implicit rule target '.c.o' is constructed and searched for. If it does not exist, the next suffix is tried. If the implicit rule target does exist, vmake looks for a file 'fred.c'. If this file does not exist, the next extension is tried. If 'fred.c' does exist, then the associated rules are executed to create fred.o from fred.c, presumably invoking the C compiler.

If the next extension must be tried, vmake reiterates the above with target '.y.o' and a file named 'fred.y', and potentially with '.l.o' and 'fred.l'.


Examples

This makefile says that pgm depends on two files a.obj and b.obj, and that they in turn depend on their corresponding source files (a.c and b.c) along with the common file incl.h.
  pgm : a.obj b.obj

$(CC) a.obj b.obj -o $@

a.obj: incl.h a.c

$(CC) -c a.c

b.obj: incl.h b.c

$(CC) -c b.c
The following makefile uses implicit rules to express the same dependencies.
  pgm : a.obj b.obj

pgm : a.obj b.obj

$(CC) a.o b.o -o $@

a.obj b.obj: incl.h


Files

   makefile
Current version(s) of make description file.


   default.mk
Default file for user-defined targets, macros, and implicit rules.

Diagnostics

vmake returns an exit status of 1 when it halts as a result of an error. Otherwise it returns an exit status of 0.
   Badly formed macro
A macro definition has been encountered which has incorrect syntax. Most likely, the name is missing.


   cannot open file
The makefile indicated in an include directive was not found or was not accessible.


   Don't know how to make target
There is no makefile entry for target, none of vmake 's implicit rules apply, and there is no .DEFAULT: rule.


   Improper Macro
An error has occurred during macro expansion. The most likely error is a missing closing bracket.


   rules must be after target
A makefile syntax error, where a line beginning with a SPACE or TAB has been encountered before a target line.


   too many options
vmake has run out of allocated space while processing command line options or a target list.

Features

vmake allows spaces as well as TABs to introduce shell command lines.


Known Problems

vmake does not allow a target line to end with a semi-colon (;) and a command. All commands must be on separate lines.

Target lines cannot use the double colon (::) syntax. Once a dependency is made, vmake assumes that the dependency file is present for the remainder of the run. If a rule subsequently removes that file and future targets depend on it's existence, unexpected errors may result.

Sometimes vmake gets confused when searching for implicit rules, and uses several rules instead of a single rule. For example, the two rules .c.o and .l.c may be used, rather than the more direct .l.o rule.

The -f options are included in MAKEFLAGS for subordinate vmakes. These are safely ignored, as long as $(MAKEFLAGS) is NOT specified on the $(MAKE) command line.

The following flags are NOT supported:
   -k
When a nonzero error status is returned by a command, abandon work on the current target, but continue with other branches that do not depend on this target.


   -p
Print out the compete set of macro definitions and target


   -P
Report dependencies recursively to show the entire dependency hierarchy, without rebuilding any targets.


   -q
Question mode. VMAKE returns a zero or non-zero status code, depending on whether or not the target file is up to date.


   -S
Undo the effect of the -k option. Stop processing when a non-zero exit status is returned by a command.
The following special targets are NOT supported:

  .KEEP_STATE:
.MAKE_VERSION:
.PRECIOUS:
.SCCS_GET: