GNU Make

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** Most importantly, <tt>svn status</tt> should not show any entries in the 'M'odified state. This indicates either generated files being checked into source control, or the build process modifying source in-place (the same thing, really)

** If <tt>svn:ignore</tt> is properly used, the following rule suffices as a project-independent <tt>clean</tt> target, assuming the presence of [[xmlstarlet]]:<pre>svn --xml --no-ignore status | xmlstarlet sel -t -m //entry -i "wc-status[@item='ignored']" -v @path -n | xargs rm -rf</pre>

==[[bash]] interactions==

* [http://www.gnu.org/s/hello/manual/make/Choosing-the-Shell.html The shell to use] can be specified via $(SHELL). By default, <tt>/bin/sh</tt> is used

** Unlike most variables, it cannot be inherited from the environment (except on Windows, where it is)

** It is not exported by default to sub-Makes, but [http://www.gnu.org/s/hello/manual/make/Variables_002fRecursion.html#Variables_002fRecursion it can be]

* Arguments to the shell can be specified via <tt>.SHELLFLAGS</tt>

** By default, it's <tt>-c</tt>, or <tt>-ec</tt> in POSIX mode

* Remember that errors in the body of a shell loop don't set the overall return value:

<pre>target:

while true ; do false ; done</pre>

This recipe cannot be successfully completed! You can use<pre>target:

set -e ; while true ; do false ; done</pre>or <pre>target:

while true ; do false || exit ; done</pre>

The former is probably nicer, since you can then use ; in the place of &&, but it deviates from expected gmake semantics. In general, you don't want to be doing this kind of thing anyway; it's useful for cases like running unit testing on a set of inputs, where outputs won't be generated.

GNU Make: Difference between revisions

Dank (talk | contribs)

@@ Line 18: / Line 18: @@
 ** Most importantly, <tt>svn status</tt> should not show any entries in the 'M'odified state. This indicates either generated files being checked into source control, or the build process modifying source in-place (the same thing, really)
 ** If <tt>svn:ignore</tt> is properly used, the following rule suffices as a project-independent <tt>clean</tt> target, assuming the presence of [[xmlstarlet]]:<pre>svn --xml --no-ignore status | xmlstarlet sel -t -m //entry -i "wc-status[@item='ignored']" -v @path -n | xargs rm -rf</pre>
+==[[bash]] interactions==
+* [http://www.gnu.org/s/hello/manual/make/Choosing-the-Shell.html The shell to use] can be specified via $(SHELL). By default, <tt>/bin/sh</tt> is used
+** Unlike most variables, it cannot be inherited from the environment (except on Windows, where it is)
+** It is not exported by default to sub-Makes, but [http://www.gnu.org/s/hello/manual/make/Variables_002fRecursion.html#Variables_002fRecursion it can be]
+* Arguments to the shell can be specified via <tt>.SHELLFLAGS</tt>
+** By default, it's <tt>-c</tt>, or <tt>-ec</tt> in POSIX mode
+* Remember that errors in the body of a shell loop don't set the overall return value:
+<pre>target:
+        while true ; do false ; done</pre>
+This recipe cannot be successfully completed! You can use<pre>target:
+        set -e ; while true ; do false ; done</pre>or <pre>target:
+        while true ; do false || exit ; done</pre>
+The former is probably nicer, since you can then use ; in the place of &&, but it deviates from expected gmake semantics. In general, you don't want to be doing this kind of thing anyway; it's useful for cases like running unit testing on a set of inputs, where outputs won't be generated.