How to set pipefail in a Makefile

Question

Consider this Makfile:

all: 
    test 1 -eq 2 | cat
    echo 'done'

It will be executed with no error.

I've heard of set -o pipefail that I may use like this:

all: 
    set -o pipefail;     \
    test 1 -eq 2 | cat;  \
    echo 'done'

Apart that it does not work, this writing is very painful.

Another solution would be to use temporary files. I would like to avoid it.

What other solution can I use?

How does that second snippet not work? It should work just fine (other than `cat` being pointless there obviously). Or did you mean that it doesn't prevent `done` from being echoed out? It doesn't do that because nothing tells the shell to stop executing. You only have a single line here not multiples so make can't terminate for the `test` failure (even though it propagates past the `| cat`). Drop the `; \` between `cat` and `echo` and it'll do what you expect. — Etan Reisner, Nov 25 '15 at 20:40
With your example code you **shouldn't** get any errors. The `test` failure just gets ignored. Nothing looks at it. You are expecting make to see it and fail the recipe but that only happens for the return code of the *entire* command (normally a single line but in your case the concatenated set of three lines). — Etan Reisner, Nov 25 '15 at 21:00
In my use case I am using a home made cksum script that I pipe into `dd -of=$@ -seek=$$(( $$(stat -c %s $@) - 4 ))`. If the cksum fail, dd should also fail and I should never execute the rest of the commands. — nowox, Nov 25 '15 at 21:10
Then if you want to use a continued line in a makefile you need to check for failure and exit yourself because make won't do that for you. `set -o pipefail; \ cksum ... | dd || exit 1; \ echo done` — Etan Reisner, Nov 25 '15 at 21:12
Or use two lines `set -o pipefail; \ cksum ... | dd ... || exit 1` and `echo done` *without* merging those together. — Etan Reisner, Nov 25 '15 at 21:15
Thanks, I've just realized it while reading your previous comment. However the syntax is very annoying. I am looking for a more definitive solution where i tell make to always enable `set -o pipefail` for all pipes. — nowox, Nov 25 '15 at 21:15
You enable it *for a given shell session*. So you need to make sure you do that for *each* session you have. Each line is a new session. If you don't want that you can use `.ONESHELL` in make 4.1 (but realize that will prevent make from **ever** bailing a recipe out for a recipe-internal non-zero return code so you get to check your commands yourself at all times.\ — Etan Reisner, Nov 25 '15 at 21:19
And this isn't a syntax problem this is a semantics issue. You don't fully grasp how make works here. — Etan Reisner, Nov 25 '15 at 21:19
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/96190/discussion-between-nowox-and-etan-reisner). — nowox, Nov 25 '15 at 21:34

score 18 · Answer 1 · edited May 23 '17 at 12:32

18

You can force pipefail on as part of make's SHELL invocation From equivalent of pipefail in GNU make?

SHELL=/bin/bash -o pipefail

edited May 23 '17 at 12:32

Community

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answered Sep 09 '16 at 21:41

John

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3

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Thanks. This should probably be the accepted answer here. Short, concise and solves it generally for all shell invocations in the `Makefile`. – Per Lundberg Sep 30 '20 at 19:11

l0b0 · Accepted Answer · 2015-11-25T20:20:50.553

3

For anything more complicated than single commands I generally prefer using a script. That way you control the interpreter completely (via the shebang line), and you can put more complicated commands together rather than trying to shoe-horn it into effectively a single line. For example:

Makefile:

all:
    ./my.sh

my.sh:

#!/usr/bin/env bash
set -o errexit -o pipefail
test 1 -eq 2 | cat
echo 'done'

That said, the exit code of a Makefile command block like the one you have is the exit code of the last command since you separate the commands with ;. You can use && to execute only until you get an error (equivalent to errexit), like this:

set -o pipefail && test 1 -eq 2 | cat && echo 'done'

edited Nov 25 '15 at 20:20

answered Nov 25 '15 at 20:17

l0b0

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This could be a solution, but then you will have dozens of scripts related to your Makefile. Then, I am wondering how do you organize it. – nowox Nov 25 '15 at 20:20
Like any other complex project, you'll want to make that complexity manageable. And a lot of scripts doing one thing each is generally a lot more manageable than a single huge makefile. – l0b0 Nov 25 '15 at 20:23
Do you know good *GitHub* projects that I can take inspiration from? – nowox Nov 25 '15 at 20:26
I've got a few [makefile includes](https://github.com/l0b0/make-includes) which I use in various other projects, but I'd just try to keep it as simple as possible. And make sure you use a real language rather than shell at every possible opportunity. The code may be longer, but you'll save yourself so much grief in terms of maintainability and testability. – l0b0 Nov 25 '15 at 20:32
That's my very problem. Today I rewrote a script written in Perl that split files by adding checksum at the end of each one for a shell script embedded into the target. I gave a try in Python, but it is too slow to work with (about 5-10 times slower than Perl which is sometime slower than pure shell script. – nowox Nov 25 '15 at 20:36
You might want to ask about that script on [codereview.SE](https://codereview.stackexchange.com/). It shouldn't be any appreciably slower in any major language than any other, and certainly not in Python. – l0b0 Nov 25 '15 at 20:44
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/96188/discussion-between-nowox-and-l0b0). – nowox Nov 25 '15 at 20:45

How to set pipefail in a Makefile

2 Answers2