Chapter 7: Conditional Parts of Makefiles 81
Substitution and Analysis], page 84). This is useful when touch is not enough to make a
file appear up to date.
The findstring function determines whether one string appears as a substring of an-
other. If you want to test for the ‘-t’ flag, use ‘t’ as the first string and the value of
MAKEFLAGS as the other.
For example, here is how to arrange to use ‘ranlib -t’ to finish marking an archive file
up to date:
archive.a: ...
ifneq (,$(findstring t,$(MAKEFLAGS)))
+touch archive.a
+ranlib -t archive.a
else
ranlib archive.a
endif
The ‘+’ prefix marks those recipe lines as “recursive” so that they will be executed despite
use of the ‘-t’ flag. See Section 5.7 [Recursive Use of make], page 50.
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