On Do, 14.09.23 03:50, Muggeridge, Matt (matt.muggerid...@hpe.com) wrote: > $ ls -l /etc/.pwd.lock > > lrwxrwxrwx 1 root root 19 Apr 5 2011 /etc/.pwd.lock -> sysconfig/.pwd.lock > > $ ls -l /etc/sysconfig/.pwd.lock > > -rw------- 1 root root 0 Aug 16 07:25 /etc/sysconfig/.pwd.lock > > For the purpose of investigation, I configured an overlay so /etc/.pwd.lock > was a simple writeable file (not a read-only symlink) and the service starts. > > Why is systemd complaining about the file being a symlink?
It's supposed to be a lock file, i.e. a regular file we issue POSIX file locks on. It's not a config file. The problem with symlinks for things like this is that in various contexts these files are atomically replaced, and if that happens then symlinks just make a mess, since it's not clear whether to replace the symlink or its target. Hence, we don't support that. Generally, things like /etc/passwd is API pretty much, you cannot really change it to a be a symlink (unless you make it fully immutable), since it is updated by various tools and these tools tend to do atomic updates of these files, i.e. when updating they write a new file under a temporary name/O_TMPFILE, and then atomically move it over the old file, so that other clients either get the old version or the new version but never a half-updated version. This kind of updating is really how you have to do things on UNIX, but that means symlinks are out of the question... Hence, TLDR: don't make the lock file a symlink. (Also, why would you even?) Lennart -- Lennart Poettering, Berlin
