On Wed, 03.02.16 22:03, Michael Biebl ([email protected]) wrote: > Hi everyone > > I wonder that emergency.target/emergency.service/emergency mode is good for. > > Afaics, it doesn't offer anything that rescue mode doesn't also offer. > I find this situation a bit confusing. > > Can anyone enlighten me why we need two different modes which are > basically the same?
Emergency mode means the only running process is a shell, besides systemd itself. rescue mode means all early-boot services have been started, all mounts have been established, and then gives you a shell. emergency mode is a bit like booting with init=/bin/sh except that you actually have systemd up properly, and can start services bit-by-bit if you like. emergency mode is also entered if fsck fails, as in that case rescue mode is unachievable, as we cannot mount the failed disks... rescue mode is usually what admins want to boot into for single-user maintainance tasks. The only reason when you want to boot into emergency mode instead if you have some fuckup with your disks. Note that sysvinit had the very same distinction, though the feature is little-known. Booting sysvinit with "emergency" on the kernel cmdline would give you just sysvinit as PID1 plus /bin/sh forked off. Booting sysvinit with "1" on the kernel cmdline would give you runlevel 1 services including mounts, and then a shell. In fact, systemd understand the same kernel cmdline keywords and does the right thing... Lennart -- Lennart Poettering, Red Hat _______________________________________________ systemd-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/systemd-devel
