Home GNU Make Manual www.imodulo.com · 2003-04-05
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Special Targets

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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 commands unconditionally, regardless of whether a file with that name exists or what its last-modification time is. Phony Targets.

.SUFFIXES

The prerequisites of the special target .SUFFIXES are the list of suffixes to be used in checking for suffix rules. Old-Fashioned Suffix Rules.

.DEFAULT

The commands specified for .DEFAULT are used for any target for which no rules are found (either explicit rules or implicit rules). Last Resort. If .DEFAULT commands are specified, every file mentioned as a prerequisite, but not as a target in a rule, will have these commands executed on its behalf. 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 commands, the target is not deleted. 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. 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. 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. 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).

.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 commands exit with a nonzero exit status, just as it does when it receives a signal. Errors in Commands.

.IGNORE

If you specify prerequisites for .IGNORE, then make will ignore errors in execution of the commands run for those particular files. The commands for .IGNORE are not meaningful.

If mentioned as a target with no prerequisites, .IGNORE says to ignore errors in execution of commands for all files. This usage of .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. Errors in Commands.

.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 commands for .LOW_RESOLUTION_TIME are not meaningful.

The high resolution file time stamps of many modern hosts lessen the chance of make incorrectly concluding that a file is up to date. Unfortunately, these hosts provide no 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 subsecond 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 subsecond 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 commands to remake those particular files before executing them. The commands for .SILENT are not meaningful.

If mentioned as a target with no prerequisites, .SILENT says not to print any commands before executing them. This usage of .SILENT is supported only for historical compatibility. We recommend you use the more selective ways to silence specific commands. Command Echoing. If you want to silence all commands for a particular run of make, use the -s or -silent option (Options Summary).

.EXPORT_ALL_VARIABLES

Simply by being mentioned as a target, this tells make to export all variables to child processes by default. 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 be run in parallel (unless its makefile contains this target). Any prerequisites on this target are ignored.

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 .. Old-Fashioned Suffix Rules.