diff options
| -rw-r--r-- | make.texinfo | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/make.texinfo b/make.texinfo index cd86828..4535f88 100644 --- a/make.texinfo +++ b/make.texinfo @@ -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 |