mktemp invocation in "install.sh" fails on older OS X images

[BanzaiMan]

What is the current behavior?

On OS X 10.10 and older, the install script fails due to incorrect mktemp invocation. The same invocation works on 10.11 and newer.

If the current behavior is a bug, please provide the steps to reproduce.

Run the following on OS X Yosemite:

curl -o- -L https://yarnpkg.com/install.sh | bash

What is the expected behavior?
Installation succeeds (or, when gpg is not available and $YARN_GPG is not set to no, the installation fails with gpg being unavailable).

Please mention your node.js, yarn and operating system version.

Node.js 6.9.1 on OS X 10.10.

See https://travis-ci.org/BanzaiMan/travis_production_test/jobs/177976869#L83

[Daniel15]

Sorry about that, I'm not very familiar with Mac OS and how it differs from Linux. Is this a BSD-ism or a MacOS-ism? What is the standard way for creating a temporary file in Mac OS X?

[BanzaiMan]

That is an excellent question. I expected mktemp to work in all cases, but it apparently does not. I honestly do not know how this was supposed to be done on older OS X releases. (I no longer have direct access to it.)

[Daniel15]

I no longer have direct access to it.

Me neither... I use Windows, and at Facebook everyone on OSX was forced to upgrade to Sierra as there's several security patches that Apple are not backporting to older OSX versions.

[Daniel15]

Got an explanation from someone internally at Facebook :)

mktemp on older macOS did not support skipping the template.
10.9 man page you can compare to mktemp(1) on your Sierra. https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man1/mktemp.1.html
So, the portable way to achieve this to actually supply the template:

tarball_tmp="$(mktemp -t yarn-tarball.XXXXXXXX)"