for build source build source
This lc &file &^file $(PWD)/&file $(abs_src)/&file
- directory any &/file &^/file $(PWD)&/file $(abs_src)/&/file
+ directory any &/file &^/file $(PWD)/&/file $(abs_src)/&/file
several & f g h &^ f g h $(addprefix...)
Top lc file &~file
The assumption is that filenames are usually lowercase and
variables usually uppercase. Otherwise, use another syntax:
+&/ => sub/dir/ or nothing
&_ => sub_dir_ or TOP_
-&=_ => sub_dir or TOP
+&. => sub/dir or .
+ (This implies that `&./' works roughly like `&/', although
+ it can produce a needless `./')
-&/ => sub/dir/ or nothing
-&=/ => sub/dir or .
+&= => sub_dir or TOP
&^lc => $(top_srcdir)/sub/dir/lc
&^/ => $(top_srcdir)/sub/dir/
+&^. => $(top_srcdir)/sub/dir
&~lc => $(top_srcdir)/lc
&~/ => $(top_srcdir)/
+&~. => $(top_srcdir)
In general:
- = return subdir without delimiter (not allowed with `^' `~')
^ pathname of this subdirectory in source tree
~ pathname of top level of source tree
- / terminates the escape (needed if next is not lwsp or space)
+ / terminates the path escape } needed if next is
+ _ terminates the var escape } not lwsp or space)
+ . terminates path escape giving dir name (excluding /)
+ = terminates var escape giving only prefix part (rarely needed)
lwsp starts multi-word processing (see below)
So pathname syntax is a subset of:
- '&' [ '^' | '~' ] [ lc | '/' ]
+ '&' [ '^' | '~' ] [ lc | '/' | '.' | '=' ]
&& => && for convenience in shell runes
-\& => & general escaping mechanism
+
+&\& => & general escaping mechanism
+&\$ => $
+&\NEWLINE eats the newline and vanishes
+
+&$VARIABLE => $(sub_dir_VARIABLE) or $(TOP_VARIABLE)
+ VARIABLE is ASCII starting with a letter and matching \w+
& thing thing... &
&^ thing thing... &
&:<directive> <args>....
recognised at start of line only (possibly after lwsp)
- args are processed for &
-&:include filename filename should usually be foo.sd.mk
+&:include filename filename should usually be [&]foo.sd.mk
&:-include filename tolerate nonexistent file
filenames are relative to $(top_srcdir)
+ RHS is &-expanded
&!<lwsp> disables & until EOL (and then disappears)
&# delete everything to end of line
(useful if the RHS contains unrecognised & constructions)
-&!STUFF
- changes the escape sequence from & to literally STUFF
- STUFF may be any series of of non-whitespace characters,
- and is terminated by EOL or lwsp. &!STUFF and the lwsp
- are discarded.
+&:changequote NEWQUOTE
+ changes the escape sequence from & to literally NEWQUOTE
+ NEWQUOTE may be any series of of non-whitespace characters,
+ and is terminated by EOL or lwsp. The whole line is
+ discarded.
- After this, write STUFF instead of &, everywhere.
+ After this, write NEWQUOTE instead of &, everywhere.
The effect is global and lasts until the next setting.
It takes effect on &:include'd files too, so maybe set
it back before using &:include.
Notably
- STUFFSTUFF => STUFFSTUFF
- \STUFF => STUFF
- STUFF!& set escape back to &
+ NEWQUOTENEWQUOTE => NEWQUOTENEWQUOTE
+ NEWQUOTE\NEWQUOTE => NEWQUOTE
+ NEWQUOTE\$ => $
+ NEWQUOTE:changequote & set escape back to &
&TARGETS_things
- Handled specially. If mentioned, declares that this
+ Handled specially. If mentioned at the start of a line
+ (possibly following whitespace), declares that this
subdir ought to have a target `things'. The rule will be
&/things:: $(&TARGETS_things)
which recursively implies this directory's `things'.
Must be spelled exactly &TARGETS_things. &_TARGETS_things,
- for example, is not magic. But mentioning &TARGETS_things in
- a #-comment *does* work because the & filter does not care
- about comments.
+ for example, is not magic. To make the target exist
+ without providing any prerequisites for it, write a line
+ containing just `&TARGETS_things +='.
`all' is extra special: every directory has an `all'
target, which corresponds to &TARGETS.
far enough to regenerate a working set of makefiles. If this happens
just rerun ./config.status by hand.
+If you go back and forth between different versions of your code you
+can sometimes find that `make' complains that one of your Subdir.sd.mk
+files is missing: typically, if iot was used and therefore a
+dependency in some other version of your code. If you run `make
+clean' (or `make realclean') these dependencies are suppressed, which
+will clear up the problem.
+
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