CODEWITHSUNDEEP
makefilegnu-make
voidvector
voidvector

Reputation: 1996

Makefile rule that doesn't generate a file, but checks dependecy

How do I write an intermediate rule that doesn't generate a target file in Makefile in such a way that it checks dependency correctly?

So I have something like this: 

install_script: xxx.sql
     psql -f $?

dump.txt: install_script
     psql -c 'select * from xxx;' > $@

I want to make sure that install_script only get run when make dump.txt if and only if xxx.sql was modified.

Upvotes: 1

Views: 108

Answers (2)

dashesy
dashesy

Reputation: 2643

You probably are looking for the phony targets in the makefile. So it should look like:

.PHONY: dump.txt
dump.txt: install_script

Upvotes: 0

Eldar Abusalimov
Eldar Abusalimov

Reputation: 25483

AFAIK, the simplest way for your case is to use a dummy intermediate file:

.xxx.sql.timestamp: xxx.sql
    psql -f $?
    @touch $@

dump.txt: .xxx.sql.timestamp
    psql -c 'select * from xxx;' > $@

And if you want to force dumping the query result unconditionally (even if everything is up-to-date), then add .PHONY target:

.PHONY : dump.txt

Upvotes: 1

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