What is the use of OR operator in dependency list?

Question

I see a build rule like the following.

a: b c | d
    some_rule

For example:

result.xml: parser.py data0.txt | data1.txt
    python parser.py data0.txt data1.txt

So, I am wondering, how would the above be different if the OR operator "|" was not used at all. What is the use of an OR operator in dependency list?

For completeness sake: it's not an "or" operator, it's a notation for order-only dependency. — Victor Sergienko, Sep 25 '20 at 06:42

score 1 · Answer 1 · answered Sep 23 '20 at 22:05

1

Short answer:
a regular prerequisite can lead to the target being rebuilt,
an order-only prerequisite doesn't force that

Long answer:
see this related answer also on SO

answered Sep 23 '20 at 22:05

Milag

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Thanks a lot. This is helpful. – anupamb Sep 23 '20 at 22:21
1

Or the documentation: https://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html – MadScientist Sep 24 '20 at 04:37

What is the use of OR operator in dependency list?

1 Answers1