vpath
Directive
Similar to the VPATH
variable, but more selective, is the
vpath
directive (note lower case), which allows you to specify a
search path for a particular class of file names: those that match a
particular pattern. Thus you can supply certain search directories for
one class of file names and other directories (or none) for other file
names.
There are three forms of the vpath
directive:
vpath pattern directories
VPATH
variable.
vpath pattern
vpath
vpath
directives.
A vpath
pattern is a string containing a `%' character. The
string must match the file name of a dependency that is being searched
for, the `%' character matching any sequence of zero or more
characters (as in pattern rules; see section Defining and Redefining Pattern Rules). For example, %.h
matches files that
end in .h
. (If there is no `%', the pattern must match the
dependency exactly, which is not useful very often.)
`%' characters in a vpath
directive's pattern can be quoted
with preceding backslashes (`\'). Backslashes that would otherwise
quote `%' characters can be quoted with more backslashes.
Backslashes that quote `%' characters or other backslashes are
removed from the pattern before it is compared to file names. Backslashes
that are not in danger of quoting `%' characters go unmolested.
When a dependency fails to exist in the current directory, if the
pattern in a vpath
directive matches the name of the
dependency file, then the directories in that directive are searched
just like (and before) the directories in the VPATH
variable.
For example,
vpath %.h ../headers
tells make
to look for any dependency whose name ends in `.h'
in the directory `../headers' if the file is not found in the current
directory.
If several vpath
patterns match the dependency file's name, then
make
processes each matching vpath
directive one by one,
searching all the directories mentioned in each directive. make
handles multiple vpath
directives in the order in which they
appear in the makefile; multiple directives with the same pattern are
independent of each other.
Thus,
vpath %.c foo vpath % blish vpath %.c bar
will look for a file ending in `.c' in `foo', then `blish', then `bar', while
vpath %.c foo:bar vpath % blish
will look for a file ending in `.c' in `foo', then `bar', then `blish'.
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