On Mon, 06 Jan 2020 at 12:12:23 +0100, Harald Dunkel wrote: > I haven't found it mentioned in the policy manual, so I wonder if > Debian is supposed to be POSIX compliant (unless noted otherwise)?
I suspect what we aim for is "approximately POSIX". Neither the Linux kernel nor the various user-space components within the scope of POSIX (mostly GNU, but probably also some non-GNU packages like util-linux) aim to be pedantically POSIX-compliant: they will implement non-POSIX-compliant behaviours if their maintainers think there is a good reason to do so. For example, GNU grep has command-line parsing behaviour that is technically not POSIX-compliant (option arguments given after filenames are interpreted as options, but POSIX says they are filenames), unless the environment variable POSIXLY_CORRECT is set: $ grep nobody /etc/passwd -v ... all of /etc/passwd, except nobody ... $ POSIXLY_CORRECT=1 grep nobody /etc/passwd -v /etc/passwd:nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin grep: -v: No such file or directory Another classic example is that POSIX requires df and du to count in 512-byte blocks, but the GNU tools default to counting 1 KiB blocks. smcv