@node Directory Search, Phony Targets, Wildcards, Rules
@section Searching Directories for Prerequisites
-@vindex VPATH
-@findex vpath
@cindex vpath
@cindex search path for prerequisites (@code{VPATH})
@cindex directory search (@code{VPATH})
prerequisite exactly, which is not useful very often.)
@cindex @code{%}, quoting in @code{vpath}
-@cindex @code{%}, quoting with @code{\} (backslash)
@cindex @code{\} (backslash), to quote @code{%}
@cindex backslash (@code{\}), to quote @code{%}
@cindex quoting @code{%}, in @code{vpath}
will be executed every time you say @samp{make clean}.
@cindex @code{rm} (shell command)
-@findex .PHONY
+@cindex using .PHONY
In this example, the @file{clean} target will not work properly if a
file named @file{clean} is ever created in this directory. Since it
has no prerequisites, @file{clean} would always be considered up to
of suffixes to be used in checking for suffix rules.
@xref{Suffix Rules, , Old-Fashioned Suffix Rules}.
-@findex .DEFAULT
+@findex .DEFAULT@r{, special target}
@item .DEFAULT
The recipe specified for @code{.DEFAULT} is used for any target for
as secondary (i.e., no target is removed because it is considered
intermediate).
-@findex .SECONDEXPANSION
@item .SECONDEXPANSION
If @code{.SECONDEXPANSION} is mentioned as a target anywhere in the
@code{.WAIT} between each prerequisite of the listed targets. @xref{Parallel
Disable, , Disabling Parallel Execution}.
-@findex .ONESHELL
@item .ONESHELL
@cindex recipe execution, single invocation
generate text.g -$(subst output,,$@@) > $@@
@end group
@end example
-@findex subst
@noindent
is equivalent to
prerequisite is the same for all targets.
@cindex @code{%}, quoting in static pattern
-@cindex @code{%}, quoting with @code{\} (backslash)
@cindex @code{\} (backslash), to quote @code{%}
@cindex backslash (@code{\}), to quote @code{%}
@cindex quoting @code{%}, in static pattern
@cindex @code{-s}
@cindex @code{--silent}
@cindex @code{--quiet}
-@findex .SILENT
The @samp{-s} or @samp{--silent}
flag to @code{make} prevents all echoing, as if all recipes
started with @samp{@@}. A rule in the makefile for the special target
,Communicating Variables to a Sub-@code{make}}), forcing it to be
passed in the environment to recipe lines.
-@vindex @code{MAKESHELL} @r{(MS-DOS alternative to @code{SHELL})}
However, on MS-DOS and MS-Windows the value of @code{SHELL} in the
environment @strong{is} used, since on those systems most users do not
set this variable, and therefore it is most likely set specifically to
on MS-DOS unaltered if you have e.g.@: @file{sh.exe} installed in some
directory along your @code{PATH}.
-@vindex SHELL
-@vindex .SHELLFLAGS
-
@node Parallel, Errors, Execution, Recipes
@section Parallel Execution
@cindex recipes, execution in parallel
parallel execution.
@cindex .NOTPARALLEL special target
-@findex .NOTPARALLEL
If the @code{.NOTPARALLEL} special target with no prerequisites is specified
anywhere then the entire instance of @code{make} will be run serially,
regardless of the parallel setting. For example:
@cindex @code{-i}
@cindex @code{--ignore-errors}
-@findex .IGNORE
When you run @code{make} with the @samp{-i} or @samp{--ignore-errors}
flag, errors are ignored in all recipes of all rules. A rule in the
makefile for the special target @code{.IGNORE} has the same effect, if
default.
@cindex Emacs (@code{M-x compile})
-@findex .DELETE_ON_ERROR
+@findex .DELETE_ON_ERROR@r{, errors in recipes}
@cindex deletion of target files
@cindex removal of target files
@cindex target, deleting on error
updating---resulting in a strange error message from the linker when it
tries to link an object file half of which is missing.
-@findex .PRECIOUS
+@cindex .PRECIOUS, preserving targets
You can prevent the deletion of a target file in this way by making the
special target @code{.PRECIOUS} depend on it. Before remaking a target,
@code{make} checks to see whether it appears on the prerequisites of
@code{export} or @code{unexport} directive should be exported. Any variable
given in an @code{unexport} directive will still @emph{not} be exported.
-@findex .EXPORT_ALL_VARIABLES
+@findex .EXPORT_ALL_VARIABLES@r{, compatibility}
@cindex compatibility in exporting
The behavior elicited by an @code{export} directive by itself was the default
in older versions of GNU @code{make}. If your makefiles depend on this
fixed limit on the size of the environment, and putting so much
information into the value of @code{MAKEFLAGS} can exceed it. If you
see the error message @samp{Arg list too long}, this may be the problem.
-@findex .POSIX
-@cindex POSIX
(For strict compliance with POSIX.2, changing @code{MAKEOVERRIDES} does
not affect @code{MAKEFLAGS} if the special target @samp{.POSIX} appears
in the makefile. You probably do not care about this.)
(@xref{Variables/Recursion, , Communicating Variables to a
Sub-@code{make}}, for information about @code{MAKELEVEL}.)
-@vindex MAKELEVEL
-@vindex MAKE
@example
@group
ifeq (0,$@{MAKELEVEL@})
substitution references as well as @code{patsubst} for compatibility
with other implementations of @code{make}.
-@findex patsubst
Another type of substitution reference lets you use the full power of
the @code{patsubst} function. It has the same form
@samp{$(@var{var}:@var{a}=@var{b})} described above, except that now
@table @code
-@vindex MAKEFILE_LIST @r{(list of parsed makefiles)}
+@vindex MAKEFILE_LIST
@cindex makefiles, and @code{MAKEFILE_LIST} variable
@cindex including (@code{MAKEFILE_LIST} variable)
@item MAKEFILE_LIST
@end group
@end example
-@vindex .DEFAULT_GOAL @r{(define default goal)}
+@vindex .DEFAULT_GOAL
@item .DEFAULT_GOAL
Sets the default goal to be used if no targets were specified on the
command line (@pxref{Goals, , Arguments to Specify the Goals}). The
Note that assigning more than one target name to @code{.DEFAULT_GOAL} is
invalid and will result in an error.
-@vindex MAKE_RESTARTS @r{(number of times @code{make} has restarted)}
+@vindex MAKE_RESTARTS
@item MAKE_RESTARTS
This variable is set only if this instance of @code{make} has
restarted (@pxref{Remaking Makefiles, , How Makefiles Are Remade}): it
this is not the same as recursion (counted by the @code{MAKELEVEL}
variable). You should not set, modify, or export this variable.
-@vindex MAKE_TERMOUT @r{(whether stdout is a terminal)}
-@vindex MAKE_TERMERR @r{(whether stderr is a terminal)}
+@vindex MAKE_TERMOUT
+@vindex MAKE_TERMERR
@item MAKE_TERMOUT
@itemx MAKE_TERMERR
When @code{make} starts it will check whether stdout and stderr will
is your responsibility to reset or unexport these variables as well,
if your makefiles rely on them.
-@vindex .RECIPEPREFIX @r{(change the recipe prefix character)}
+@vindex .RECIPEPREFIX
@item .RECIPEPREFIX
The first character of the value of this variable is used as the
character make assumes is introducing a recipe line. If the variable
The value of @code{.RECIPEPREFIX} can be changed multiple times; once set
it stays in effect for all rules parsed until it is modified.
-@vindex .VARIABLES @r{(list of variables)}
+@vindex .VARIABLES
@item .VARIABLES
Expands to a list of the @emph{names} of all global variables defined
so far. This includes variables which have empty values, as well as
to this variable will be ignored; it will always return its special
value.
-@c @vindex .TARGETS @r{(list of targets)}
+@c @vindex .TARGETS
@c @item .TARGETS
@c The second special variable is @code{.TARGETS}. When expanded, the
@c value consists of a list of all targets defined in all makefiles read
@c file must appear as a target, on the left-hand side of a ``:'', to be
@c considered a target for the purposes of this variable.
-@vindex .FEATURES @r{(list of supported features)}
+@vindex .FEATURES
@item .FEATURES
Expands to a list of special features supported by this version of
@code{make}. Possible values include, but are not limited to:
Supports the @code{undefine} directive. @xref{Undefine Directive}.
@end table
-@vindex .INCLUDE_DIRS @r{(list of include directories)}
+@vindex .INCLUDE_DIRS
@item .INCLUDE_DIRS
Expands to a list of directories that @code{make} searches for
included makefiles (@pxref{Include, , Including Other Makefiles}).
Note that modifying this variable's value does not change the list of
directories which are searched.
-@vindex .EXTRA_PREREQS @r{(prerequisites not added to automatic variables)}
+@vindex .EXTRA_PREREQS
@item .EXTRA_PREREQS
Each word in this variable is a new prerequisite which is added to
targets for which it is set. These prerequisites differ from normal
this way; any subsequent @samp{%} is unchanged.
@cindex @code{%}, quoting in @code{patsubst}
-@cindex @code{%}, quoting with @code{\} (backslash)
@cindex @code{\} (backslash), to quote @code{%}
@cindex backslash (@code{\}), to quote @code{%}
@cindex quoting @code{%}, in @code{patsubst}
was given to those two functions.
@item $(wildcard @var{pattern})
-@findex wildcard
@cindex wildcard, function
The argument @var{pattern} is a file name pattern, typically containing
wildcard characters (as in shell file name patterns). The result of
@node Conditional Functions, Let Function, File Name Functions, Functions
@section Functions for Conditionals
-@findex if
@cindex conditional expansion
There are four functions that provide conditional expansion. A key
aspect of these functions is that not all of the arguments are
@node Warnings, Temporary Files, Testing, Running
@section Makefile Warnings
@cindex warnings
+@cindex enabling warnings
GNU Make can detect some types of incorrect usage in makefiles. When one of
these incorrect usages is detected, GNU Make can perform one of these actions:
line option, or using the @code{.WARNINGS} variable.
@subsubheading The @code{.WARNINGS} variable
-@findex .WARNINGS
+@vindex .WARNINGS
Warning control options provided in the @code{.WARNINGS} variable take effect
as soon as the variable assignment is parsed and will last until this instance
of @code{make} finishes parsing all makefiles. These settings will not be
Rules, , Canceling Implicit Rules}). They simply enter the suffix or
pair of suffixes concatenated as a target in the data base.
-@findex .SUFFIXES
The known suffixes are simply the names of the prerequisites of the special
target @code{.SUFFIXES}. You can add your own suffixes by writing a rule
for @code{.SUFFIXES} that adds more prerequisites, as in:
On MS-DOS only, the name of the command interpreter that is to be used
by @code{make}. This value takes precedence over the value of
-@code{SHELL}. @xref{Execution, ,MAKESHELL variable}.
+@code{SHELL}. @xref{Choosing the Shell}.
@item MAKE
projects / thirdparty / make.git / commitdiff
