When the option --enable-systemd was introduced in August 2023, it was experimental, because the code that uses it (readutmp in gnulib) was new and not widely tested. Things have changed now: Ubuntu 25.04 ships with no /var/run/utmp support and thus requires the use of the systemd libraries; without it, the 'who' program prints nothing. So, I don't think it's experimental any more.
There are two problem with this configure option: 1) Users are not aware that it is ineffective if the package 'libsystemd-dev' has not been installed. Witnesses: - Comment #11 in https://bugs.launchpad.net/ubuntu/+source/coreutils/+bug/2103489 - I tried to build coreutils-9.7 on Ubuntu 25.04. I used the option --enabled-systemd and was then surprised to see that 'who' produced no output and 'ldd src/who' did not show any systemd library. There is no mention of this build dependency anywhere in coreutils. Only gnulib/DEPENDENCIES has it documented, and the comments of m4/systemd.m4. 2) The option --enable-systemd is off by default. On systems like Ubuntu 25.04 (without /var/run/utmp support) this leads to a dysfunctional 'who' program by default. What can be done about this? Ad 1) (a) One should add a coreutils/DEPENDENCIES file that contains the relevant subset of gnulib/DEPENDENCIES, and coreutils/README-install should reference it. (b) If --enable-systemd is specified by the user and libsystemd-dev is not installed, the configuration should err out. (c) The configuration should, at the end, print a summary of which features are enabled and which are not. Like QEMU's configure does, or the one of many of Simon Josefsson's packages. Opinions? Ad 2) (a) The option --enable-systemd should be enabled by default on systems that have systemd and where /var/run/utmp does not exist. (b) The option --enable-systemd should be enabled by default on systems which have libsystemd-dev installed. Opinions? My preferences would be 1(a) + 1(c) + 2(a). And yours (with rationale)? Bruno
