diff options
Diffstat (limited to 'make.texinfo')
| -rw-r--r-- | make.texinfo | 144 |
1 files changed, 94 insertions, 50 deletions
diff --git a/make.texinfo b/make.texinfo index 9fe3550..c3d5912 100644 --- a/make.texinfo +++ b/make.texinfo @@ -10,8 +10,8 @@ @set RCSID $Id$ @set EDITION 0.47 DRAFT @set VERSION 3.72 Beta -@set UPDATED 24 October 1994 -@set UPDATE-MONTH October 1994 +@set UPDATED 1 November 1994 +@set UPDATE-MONTH November 1994 @set ISBN 1-882114-50-7 @c finalout @@ -2141,24 +2141,28 @@ match that file's name. @findex .IGNORE @item .IGNORE -Simply by being mentioned as a target, @code{.IGNORE} says to ignore -errors in execution of commands. The dependencies and commands for -@code{.IGNORE} are not meaningful. +If you specify dependencies for @code{.IGNORE}, then @code{make} will +ignore errors in execution of the commands run for those particular +files. The commands for @code{.IGNORE} are not meaningful. -@samp{.IGNORE} exists for historical compatibility. Since -@code{.IGNORE} affects every command in the makefile, it is not very -useful; we recommend you use the more selective ways to ignore errors -in specific commands. @xref{Errors, ,Errors in Commands}. +If mentioned as a target with no dependencies, @code{.IGNORE} says to +ignore errors in execution of commands for all files. This usage of +@samp{.IGNORE} is supported only for historical compatibility. Since +this affects every command in the makefile, it is not very useful; we +recommend you use the more selective ways to ignore errors in specific +commands. @xref{Errors, ,Errors in Commands}. @findex .SILENT @item .SILENT -Simply by being mentioned as a target, @code{.SILENT} says not to -print commands before executing them. The dependencies and commands -for @code{.SILENT} are not meaningful. +If you specify dependencies for @code{.SILENT}, then @code{make} will +not the print commands to remake those particular files before executing +them. The commands for @code{.SILENT} are not meaningful. -@samp{.SILENT} exists for historical compatibility. We recommend you -use the more selective ways to silence specific commands. +If mentioned as a target with no dependencies, @code{.SILENT} says not +to print any commands before executing them. This usage of +@samp{.SILENT} is supported only for historical compatibility. We +recommend you use the more selective ways to silence specific commands. @xref{Echoing, ,Command Echoing}. If you want to silence all commands for a particular run of @code{make}, use the @samp{-s} or @w{@samp{--silent}} option (@pxref{Options Summary}). @@ -2721,7 +2725,7 @@ actually doing them. The @samp{-s} or @samp{--silent} flag to @code{make} prevents all echoing, as if all commands started with @samp{@@}. A rule in the makefile for the special target -@code{.SILENT} has the same effect +@code{.SILENT} without dependencies has the same effect (@pxref{Special Targets, ,Special Built-in Target Names}). @code{.SILENT} is essentially obsolete since @samp{@@} is more flexible.@refill @@ -2910,10 +2914,10 @@ This causes @code{rm} to continue even if it is unable to remove a file. @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 commands of all rules. A rule in the makefile for the special target -@code{.IGNORE} has the same effect. These ways of ignoring errors are -obsolete because @samp{-} is more flexible. +flag, errors are ignored in all commands of all rules. A rule in the +makefile for the special target @code{.IGNORE} has the same effect, if +there are no dependencies. These ways of ignoring errors are obsolete +because @samp{-} is more flexible. When errors are to be ignored, because of either a @samp{-} or the @samp{-i} flag, @code{make} treats an error return just like success, @@ -2926,6 +2930,7 @@ can any other that depends on it either directly or indirectly. No further commands will be executed for these targets, since their preconditions have not been achieved. + @cindex @code{-k} @cindex @code{--keep-going} Normally @code{make} gives up immediately in this circumstance, returning a @@ -2947,11 +2952,28 @@ is why Emacs' @code{compile} command passes the @samp{-k} flag by default. @cindex Emacs (@code{M-x compile}) +@findex .DELETE_ON_ERROR +@cindex deletion of target files +@cindex removal of target files +@cindex target, deleting on error +Usually when a command fails, if it has changed the target file at all, +the file is corrupted and cannot be used---or at least it is not +completely updated. Yet the file's timestamp says that it is now up to +date, so the next time @code{make} runs, it will not try to update that +file. The situation is just the same as when the command is killed by a +signal; @pxref{Interrupts}. So generally the right thing to do is to +delete the target file if the command fails after beginning to change +the file. @code{make} will do this if @code{.DELETE_ON_ERROR} appears +as a target. This is almost always what you want @code{make} to do, but +it is not historical practice; so for compatibility, you must explicitly +request it. + @node Interrupts, Recursion, Errors, Commands @section Interrupting or Killing @code{make} @cindex interrupt @cindex signal @cindex deletion of target files +@cindex removal of target files @cindex target, deleting on interrupt @cindex killing (interruption) @@ -3042,28 +3064,6 @@ is @samp{cd subdir; /bin/make}. If you use a special version of executed for recursive invocations. @cindex @code{cd} (shell command) -Also, any arguments that define variable values are added to @code{MAKE}, -so the sub-@code{make} gets them too. Thus, if you do @samp{make -CFLAGS=-O}, so that all C compilations will be optimized, the -sub-@code{make} is run with @samp{cd subdir; /bin/make CFLAGS=-O}.@refill - -@vindex MAKE_COMMAND -@vindex MAKEOVERRIDES -The @code{MAKE} variable actually just refers to two other variables -which contain these special values. In fact, @code{MAKE} is always -defined as @samp{$(MAKE_COMMAND) $(MAKEOVERRIDES)}. The variable -@code{MAKE_COMMAND} is the file name with which @code{make} was invoked -(such as @file{/bin/make}, above). The variable @code{MAKEOVERRIDES} -contains definitions for the variables defined on the command line; in -the above example, its value is @samp{CFLAGS=-O}. If you @emph{do not} -want these variable definitions done in all recursive @code{make} -invocations, you can redefine the @code{MAKEOVERRIDES} variable to -remove them. You do this in any of the normal ways for defining -variables: in a makefile (@pxref{Setting, ,Setting Variables}); on the command -line with an argument like @samp{MAKEOVERRIDES=} -(@pxref{Overriding, ,Overriding Variables}); or with an environment variable -(@pxref{Environment, ,Variables from the Environment}). - As a special feature, using the variable @code{MAKE} in the commands of a rule alters the effects of the @samp{-t} (@samp{--touch}), @samp{-n} (@samp{--just-print}), or @samp{-q} (@w{@samp{--question}}) option. @@ -3106,9 +3106,9 @@ commands, is propagated to the subsystem.@refill Variable values of the top-level @code{make} can be passed to the sub-@code{make} through the environment by explicit request. These variables are defined in the sub-@code{make} as defaults, but do not -override what is specified in the sub-@code{make}'s makefile unless -you use the @samp{-e} switch -(@pxref{Options Summary, ,Summary of Options}).@refill +override what is specified in the makefile used by the sub-@code{make} +makefile unless you use the @samp{-e} switch (@pxref{Options Summary, +,Summary of Options}).@refill To pass down, or @dfn{export}, a variable, @code{make} adds the variable and its value to the environment for running each command. The @@ -3126,6 +3126,15 @@ The special variables @code{SHELL} and @code{MAKEFLAGS} are always exported (unless you unexport them). @code{MAKEFILES} is exported if you set it to anything. +@code{make} automatically passes down variable values that were defined +on the command line, by putting them in the @code{MAKEFLAGS} variable. +@iftex +See the next section. +@end iftext +@ifinfo +@xref{Options/Recursion}. +@end ifinfo + Variables are @emph{not} normally passed down if they were created by default by @code{make} (@pxref{Implicit Variables, ,Variables Used by Implicit Rules}). The sub-@code{make} will define these for @@ -3274,6 +3283,15 @@ in its environment. In response, it takes the flags from that value and processes them as if they had been given as arguments. @xref{Options Summary, ,Summary of Options}. +@cindex command line variable definitions, and recursion +@cindex variables, command line, and recursion +@cindex recursion, and command line variable definitions +Likewise variables defined on the command line are passed to the +sub-@code{make} through @code{MAKEFLAGS}. Words in the value of +@code{MAKEFLAGS} that contain @samp{=}, @code{make} treats as variable +definitions just as if they appeared on the command line. +@xref{Overriding, ,Overriding Variables}. + @cindex @code{-C}, and recursion @cindex @code{-f}, and recursion @cindex @code{-I}, and recursion @@ -3323,13 +3341,39 @@ subsystem: cd subdir; $(MAKE) MAKEFLAGS= @end example +@vindex MAKEOVERRIDES +The command line variable definitions really appear in the variable +@code{MAKEOVERRIDES}, and @code{MAKEFLAGS} contains a reference to this +variable. If you do want to pass flags down normally, but don't want to +pass down the command line variable definitions, you can reset +@code{MAKEOVERRIDES} to empty, like this: + +@example +MAKEOVERRIDES = +@end example + +@noindent +@cindex Arg list too long +@cindex E2BIG +This is not usually useful to do. However, some systems have a small +fixed limit on the size of the environment, and putting so much +information in 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.2 +(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.) + @vindex MFLAGS -A similar variable @code{MFLAGS} exists also, for historical compatibility. -It has the same value as @code{MAKEFLAGS} except that it always begins with -a hyphen unless it is empty (@code{MAKEFLAGS} begins with a hyphen only when -it begins with an option that has no single-letter version, such as -@samp{--warn-undefined-variables}). @code{MFLAGS} was traditionally used -explicitly in the recursive @code{make} command, like this: +A similar variable @code{MFLAGS} exists also, for historical +compatibility. It has the same value as @code{MAKEFLAGS} except that it +does not contain the command line variable definitions, and it always +begins with a hyphen unless it is empty (@code{MAKEFLAGS} begins with a +hyphen only when it begins with an option that has no single-letter +version, such as @samp{--warn-undefined-variables}). @code{MFLAGS} was +traditionally used explicitly in the recursive @code{make} command, like +this: @example subsystem: |