Make/Special-Targets
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4.9 Special Built-in Target Names
Certain names have special meanings if they appear as targets.
.PHONY
The prerequisites of the special target .PHONY
are considered to
be phony targets. When it is time to consider such a target,
make
will run its recipe unconditionally, regardless of
whether a file with that name exists or what its last-modification
time is. See Phony Targets.
.SUFFIXES
The prerequisites of the special target .SUFFIXES
are the list
of suffixes to be used in checking for suffix rules.
See Old-Fashioned Suffix Rules.
.DEFAULT
The recipe specified for .DEFAULT
is used for any target for
which no rules are found (either explicit rules or implicit rules).
See Last Resort. If a .DEFAULT
recipe is specified, every
file mentioned as a prerequisite, but not as a target in a rule, will have
that recipe executed on its behalf. See Implicit Rule Search Algorithm.
.PRECIOUS
The targets which .PRECIOUS
depends on are given the following
special treatment: if make
is killed or interrupted during the
execution of their recipes, the target is not deleted.
See Interrupting or Killing make
. Also, if the
target is an intermediate file, it will not be deleted after it is no
longer needed, as is normally done. See Chains of
Implicit Rules. In this latter respect it overlaps with the
.SECONDARY
special target.
You can also list the target pattern of an implicit rule (such as
‘%.o
’) as a prerequisite file of the special target .PRECIOUS
to preserve intermediate files created by rules whose target patterns
match that file’s name.
.INTERMEDIATE
The targets which .INTERMEDIATE
depends on are treated as
intermediate files. See Chains of Implicit Rules.
.INTERMEDIATE
with no prerequisites has no effect.
.SECONDARY
The targets which .SECONDARY
depends on are treated as
intermediate files, except that they are never automatically deleted.
See Chains of Implicit Rules.
.SECONDARY
with no prerequisites causes all targets to be treated
as secondary (i.e., no target is removed because it is considered
intermediate).
.SECONDEXPANSION
If .SECONDEXPANSION
is mentioned as a target anywhere in the
makefile, then all prerequisite lists defined after it appears
will be expanded a second time after all makefiles have been read in.
See Secondary Expansion.
.DELETE_ON_ERROR
If .DELETE_ON_ERROR
is mentioned as a target anywhere in the
makefile, then make
will delete the target of a rule if it has
changed and its recipe exits with a nonzero exit status, just as it
does when it receives a signal. See Errors in Recipes.
.IGNORE
If you specify prerequisites for .IGNORE
, then make
will
ignore errors in execution of the recipe for those particular files.
The recipe for .IGNORE
(if any) is ignored.
If mentioned as a target with no prerequisites, .IGNORE
says to
ignore errors in execution of recipes for all files. This usage of
‘.IGNORE
’ is supported only for historical compatibility. Since
this affects every recipe in the makefile, it is not very useful; we
recommend you use the more selective ways to ignore errors in specific
recipes. See Errors in Recipes.
.LOW_RESOLUTION_TIME
If you specify prerequisites for .LOW_RESOLUTION_TIME
,
make
assumes that these files are created by commands that
generate low resolution time stamps. The recipe for the
.LOW_RESOLUTION_TIME
target are ignored.
The high resolution file time stamps of many modern file systems
lessen the chance of make
incorrectly concluding that a file
is up to date. Unfortunately, some hosts do not provide a way to set a
high resolution file time stamp, so commands like ‘cp -p
’ that
explicitly set a file’s time stamp must discard its sub-second part.
If a file is created by such a command, you should list it as a
prerequisite of .LOW_RESOLUTION_TIME
so that make
does not mistakenly conclude that the file is out of date. For
example:
.LOW_RESOLUTION_TIME: dst dst: src cp -p src dst
Since ‘cp -p
’ discards the sub-second part of src
’s time
stamp, dst
is typically slightly older than src
even when
it is up to date. The .LOW_RESOLUTION_TIME
line causes
make
to consider dst
to be up to date if its time stamp
is at the start of the same second that src
’s time stamp is in.
Due to a limitation of the archive format, archive member time stamps
are always low resolution. You need not list archive members as
prerequisites of .LOW_RESOLUTION_TIME
, as make
does this
automatically.
.SILENT
If you specify prerequisites for .SILENT
, then make
will
not print the recipe used to remake those particular files before
executing them. The recipe for .SILENT
is ignored.
If mentioned as a target with no prerequisites, .SILENT
says
not to print any recipes before executing them. You may also use more
selective ways to silence specific recipe command lines.
See Recipe Echoing. If you want to silence all recipes
for a particular run of make
, use the ‘-s
’ or
‘--silent
’ option (see Options Summary).
.EXPORT_ALL_VARIABLES
Simply by being mentioned as a target, this tells make
to
export all variables to child processes by default.
See Communicating Variables to a
Sub-make
.
.NOTPARALLEL
If .NOTPARALLEL
is mentioned as a target, then this invocation
of make
will be run serially, even if the ‘-j
’ option is
given. Any recursively invoked make
command will still run
recipes in parallel (unless its makefile also contains this target).
Any prerequisites on this target are ignored.
.ONESHELL
If .ONESHELL
is mentioned as a target, then when a target is
built all lines of the recipe will be given to a single invocation of
the shell rather than each line being invoked separately
(see Recipe Execution).
.POSIX
If .POSIX
is mentioned as a target, then the makefile will be
parsed and run in POSIX-conforming mode. This does not mean
that only POSIX-conforming makefiles will be accepted: all advanced
GNU make
features are still available. Rather, this target
causes make
to behave as required by POSIX in those areas
where make
’s default behavior differs.
In particular, if this target is mentioned then recipes will be
invoked as if the shell had been passed the -e
flag: the first
failing command in a recipe will cause the recipe to fail immediately.
Any defined implicit rule suffix also counts as a special target if it
appears as a target, and so does the concatenation of two suffixes, such
as ‘.c.o
’. These targets are suffix rules, an obsolete way of
defining implicit rules (but a way still widely used). In principle, any
target name could be special in this way if you break it in two and add
both pieces to the suffix list. In practice, suffixes normally begin with
‘.
’, so these special target names also begin with ‘.
’.
See Old-Fashioned Suffix Rules.
Next: Multiple Targets, Previous: Empty Targets, Up: Rules [Contents][Index]