78 lines
2.2 KiB
Markdown
78 lines
2.2 KiB
Markdown
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% redo-ifchange(1) Redo 0.00
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% Avery Pennarun <apenwarr@gmail.com>
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% 2010-12-12
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# NAME
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redo-ifchange - rebuild target files when source files have changed
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# SYNOPSIS
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redo-ifchange [targets...]
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# DESCRIPTION
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Normally redo-ifchange is run from a .do file that has been
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executed by `redo`(1). See `redo`(1) for more details.
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redo-ifchange doesn't take any command line options other
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than a list of *targets*. To provide command line options,
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you need to run `redo` instead.
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redo-ifchange performs the following steps:
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- it creates a dependency on the given *targets*. If any
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of those targets change in the future, the current target
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(the one calling redo-ifchange) will marked as needing to
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be rebuilt.
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- for any *target* that is out of date, it calls the
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equivalent of `redo target`.
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- for any *target* that is locked (because some other
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instance of `redo` or `redo-ifchange` is already building
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it), it waits until the lock is released.
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redo-ifchange returns only after all the given
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*targets* are known to be up to date.
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# TIP
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You don't have to run redo-ifchange *before* generating
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your target; you can generate your target first, then
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declare its dependencies. For example, as part of
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compiling a .c file, gcc learns the list
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of .h files it depends on. You can pass this information
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along to redo-ifchange, so if any of those headers are
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changed or deleted, your .c file will be rebuilt:
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redo-ifchange $1$2
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gcc -o $3 -c $1$2 \
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-MMD -MF $1.deps -MT DELETE_ME
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redo-ifchange $(sed -e 's,^DELETE_ME:,,' \
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-e 's,\\,,' $1.deps)
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This is much less confusing than the equivalent
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autodependency mechanism in `make`(1), because make
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requires that you declare all your dependencies before
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running the target build commands.
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# REDO
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Part of the `redo`(1) suite.
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# CREDITS
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The original concept for `redo` was created by D. J.
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Bernstein and documented on his web site
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(http://cr.yp.to/redo.html). This independent implementation
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was created by Avery Pennarun and you can find its source
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code at http://github.com/apenwarr/redo.
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# SEE ALSO
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`redo`(1), `redo-ifcreate`(1), `redo-always`(1), `redo-stamp`(1)
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