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Formerly make.texinfo.~24~

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Robert J. Chassell 1992-06-12 03:51:46 +00:00
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make.texinfo
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@ -2459,24 +2459,24 @@ As a special feature, using the variable @code{MAKE} in the commands of a
rule alters the effects of the @samp{-t}, @samp{-n} or @samp{-q} option.
(@xref{Instead of Execution, ,Instead of Executing the Commands}.)@refill
@c !!! Check with Roland --rjc 9mar92
@c Is the following correct?
Consider the command @samp{make -t} in the above example. (The
@samp{make -t} option marks targets as up to date without actually
doing anything.) Following the usual
@samp{-t} option marks targets as up to date without actually running
any commands; @pxref{Instead of Execution}.) Following the usual
definition of @samp{-t}, a @samp{make -t} command in the example would
create a file named @file{subsystem} and do nothing else. What you
really want it to do is run @samp{cd subdir; make -t}; but that would
require executing the command, and @samp{-t} says not to execute
commands.@refill
The special feature makes this do what you want: whenever a rule's commands
use the variable @code{MAKE}, the flags @samp{-t}, @samp{-n} or @samp{-q}
do not apply to that rule. The commands of that rule are executed normally
despite the presence of a flag that causes most commands not to be run.
The usual @code{MAKEFLAGS} mechanism passes the flags to the
sub-@code{make} (@pxref{Options/Recursion, ,Communicating Options to a Sub-@code{make}}), so your request to touch the
files, or print the commands, is propagated to the subsystem.@refill
@strong{ !! This is wrong. It is per-command line, not per-rule. --roland }
The special feature makes this do what you want: whenever a rule's
commands use the variable @code{MAKE}, the flags @samp{-t}, @samp{-n} and
@samp{-q} do not apply to that rule. The commands of that rule are
executed normally despite the presence of a flag that causes most
commands not to be run. The usual @code{MAKEFLAGS} mechanism passes the
flags to the sub-@code{make} (@pxref{Options/Recursion, ,Communicating
Options to a Sub-@code{make}}), so your request to touch the files, or
print the commands, is propagated to the subsystem.@refill
@node Variables/Recursion, Options/Recursion, MAKE Variable, Recursion
@subsection Communicating Variables to a Sub-@code{make}
@ -2566,6 +2566,15 @@ default, variables whose names contain characters other than
alphanumerics and underscores will not be exported unless specifically
mentioned in an @code{export} directive.@refill
@findex .EXPORT_ALL_VARIABLES
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 behavior and you want to be compatible with old versions of
@code{make}, you can write a rule for the special target
@code{.EXPORT_ALL_VARIABLES} instead of the @code{export} directive.
This will be ignored by old @code{make}s, while the @code{export}
directive will cause a syntax error.@refill
Likewise, you can use @code{unexport} by itself to tell @code{make}
@emph{not} to export variables by default. Since this is the default
behavior, you would only need to do this if @code{export} had been used