Best Linux Init Systems in 2026: systemd, OpenRC, runit, s6, dinit and More

Every Linux system boots the same way. The kernel starts, mounts the root filesystem and launches one program: the init system. Everything else on your machine, from the network stack to your desktop, runs because init started it.

Most distros ship systemd, and most people never think about it again. That changes when you want a lighter system, simpler service files or a distro without systemd, or when you get curious about what is running as PID 1 on your box. This guide compares the best Linux init systems in 2026: what each does well, where it falls short, which distros ship it and who should bother switching.

The short answer: systemd is the right choice for most people. If you want something lighter, OpenRC (familiar shell scripts), runit (the simplest to run) and dinit (dependency handling without the bulk) are the strongest alternatives. s6 suits people who want maximum rigor and lean container images. SysVinit is for legacy systems and anyone who wants a boot process they can read top to bottom.

Jump to:

• Comparison table
• What an init system is
• The best init systems reviewed
• What a service looks like in each one
• Why change your default init system
• Linux distros without systemd
• How to choose
• FAQ

Linux Init Systems Compared at a Glance

Here is how the main options stack up before we go through each one.

Supervision means the init system watches a service and restarts it if it dies. Dependencies means it starts services in the right order without you numbering scripts by hand.

What Is a Linux Init System?

An init system is the first process the Linux kernel starts after boot. It runs as PID 1, the ancestor of every other process on the machine, and its job is to start services, keep them running and shut the system down cleanly.

In practice that covers three tasks:

• Bring the system up. Mount filesystems, set the hostname and start services in a workable order.
• Manage services. Start, stop and restart daemons such as SSH, your web server or the display manager.
• Shut down cleanly. Stop services, sync and unmount filesystems, then hand control back to the kernel.

PID 1 also adopts orphaned processes and reaps zombies. If PID 1 ever exits, the kernel panics, which is why init code tends to be conservative.

Init, service manager and supervisor are different jobs

People use “init system” as a catch-all, but three roles hide inside it:

• Init is PID 1 itself. It handles early boot, signals, zombie cleanup and shutdown.
• A service manager starts and stops services and tracks which ones depend on which.
• A supervisor watches running processes and restarts them when they crash.

systemd, dinit and GNU Shepherd do all three. OpenRC is mainly a service manager that normally runs on top of another PID 1. runit and s6 are supervisors with small init layers. SysVinit and BusyBox init start scripts and do little else. Knowing which role a tool covers explains most of the differences in the table above.

Where init fits in the boot process

1. The firmware (UEFI or BIOS) initializes the hardware.
2. The bootloader, such as GRUB or systemd-boot, loads the kernel and an initramfs.
3. The kernel starts, runs the initramfs and mounts the real root filesystem.
4. The kernel launches /sbin/init, or whatever the init= kernel parameter points to. This is PID 1.
5. The init system starts services and brings you to a login prompt or desktop session.

How to check which init system you are running

ps -p 1 -o comm=
readlink -f /sbin/init

The first command prints the name of PID 1. Common results are systemd, runit, dinit, openrc-init, shepherd and s6-svscan (the PID 1 process when s6-linux-init is used). A plain init means SysVinit or BusyBox. The second command shows whether /sbin/init is the BusyBox binary or a standalone init.

The Best Linux Init Systems Reviewed

These are the eight init systems worth knowing, in rough order of how likely you are to meet them. Each section covers what it is, what it does well, where it hurts and who it suits.

1. systemd: The Default Almost Everyone Runs

systemd is the default init on nearly every major distro. Fedora made the switch in 2011, Arch followed in 2012, RHEL 7 in 2014, and Debian and Ubuntu in 2015. Lennart Poettering and Kay Sievers started it as a PID 1 replacement, and it grew into a full suite that also handles logging, login sessions, timers, device events and more.

The name causes confusion, so precision helps. systemd is a collection of programs. The PID 1 manager is the core, and extras such as networkd, resolved and timesyncd are optional components you can leave disabled. The project keeps widening its scope, though. Version 261, released in June 2026, added an instance metadata service for cloud VMs, a storagectl tool and a text-mode OS installer called systemd-sysinstall. Version 260 removed support for legacy SysV init scripts, so any service that ships only a script now needs a native unit file.

Key features

• Unit files for services, sockets, timers, mounts, paths and targets
• Parallel startup based on a dependency graph, plus socket and D-Bus activation
• Process tracking and resource limits through cgroups
• journald for structured logging, read with journalctl
• Timer units that can replace cron jobs
• Sandboxing options such as ProtectSystem=, PrivateTmp= and NoNewPrivileges=, plus systemd-analyze security to score a service
• Per-user services through systemctl --user
• Boot analysis with systemd-analyze blame and systemd-analyze critical-chain

Pros

• The same commands and unit file format work on almost every major distro, so your skills transfer.
• Strong built-in tooling makes boot problems easy to trace.
• Sandboxing and resource control are well ahead of most alternatives.
• Upstream projects ship unit files, so most server software works with no extra effort.
• Documentation, forum answers and enterprise support are the deepest of any init system.

Cons

• The scope is large. Many users object to one project owning init, logging, login, DNS and more.
• A bigger codebase means more attack surface and more to understand.
• Journals are binary by default, so you need journalctl or log forwarding to read them as text.
• It is Linux-only, built around cgroups and other kernel features, so it will not run on the BSDs.
• It is heavier than needed for tiny systems and single-service containers.

The long-running arguments about systemd are mostly about scope and philosophy. On the question of whether it works, the answer is yes, which is a big reason it won.

Best for: desktops, laptops, servers and anyone who wants the path of least resistance.

Used by: Debian, Ubuntu, Fedora, RHEL and its clones, Arch Linux, openSUSE, NixOS and most mainstream distros.

2. OpenRC: Familiar Scripts, Lighter Footprint

OpenRC started in the late 2000s as a rewrite of Gentoo’s init scripts. It is a dependency-based service manager that normally pairs with another PID 1: SysVinit on Gentoo, BusyBox init on Alpine. Since version 0.25 it also ships its own optional PID 1, openrc-init. It runs on Linux, FreeBSD and NetBSD.

Key features

• Init scripts written in POSIX shell with #!/sbin/openrc-run and a depend() function that declares need, use, want, before, after and provide
• Runlevels such as boot, default and shutdown, managed with rc-update
• Service control with rc-service and status checks with rc-status
• Optional parallel startup through the rc_parallel setting
• Optional process supervision through supervise-daemon
• cgroup support and per-service settings in /etc/conf.d

Pros

• Easy to read and write if you know shell.
• Light on memory and disk, with plain-text logs and no bundled extras.
• Dependency handling replaces numbered symlinks.
• It slots in under an existing init, so you can adopt it gradually.
• Mature and well documented, especially on the Gentoo and Alpine wikis.

Cons

• Supervision is opt-in and less polished than in runit, s6 or systemd.
• No timers or socket activation, and sandboxing options are far more limited than systemd’s.
• Upstream projects rarely ship OpenRC scripts, so distro packagers write them.
• Parallel startup is off by default.
• Desktops need elogind or seatd for session handling.

Best for: Gentoo, Alpine and Artix users, lean servers and anyone who wants startup logic they can read.

Used by: Gentoo, Alpine Linux, Artix Linux (option) and Devuan (option).

3. runit: The Simplest Supervised Init

runit is a small init and supervision suite written by Gerrit Pape in the early 2000s. It follows the daemontools school of design: every service is a directory, every service has an executable run script, and a supervisor restarts the service whenever it exits. It runs on Linux, the BSDs, macOS and Solaris.

Key features

• Three-stage boot: stage 1 for one-time setup, stage 2 for running services, stage 3 for shutdown
• runsvdir and runsv supervise services automatically, controlled with the sv command
• Enabling a service means symlinking its directory into the service directory (/var/service on Void)
• Per-service logging with svlogd and size-based rotation
• A tiny code base with no daemon beyond the supervisor tree

Pros

• Extremely small and fast.
• Clear mental model: one directory, one script, one supervised process.
• A basic service is a two-line script.
• Crashed services come back automatically.
• Easy to debug because there is no hidden state.

Cons

• No dependency management. Everything starts in parallel, so you handle ordering yourself with sv check or retry loops.
• No timers, socket activation, cgroup integration or sandboxing.
• Releases are infrequent and the community is small.
• Desktops and Wayland compositors need elogind or seatd.

Best for: Void Linux users, lean servers and anyone who wants a supervised system that stays out of the way.

Used by: Void Linux, with options on Artix, Devuan and antiX.

4. s6: Rigorous, Tiny and Built for Containers

s6 is a supervision suite by Laurent Bercot of skarnet.org. On its own it supervises processes. Add s6-rc and you get a service manager with dependencies, and add s6-linux-init and you get a complete PID 1 for Linux. The pieces are small C programs designed with unusual care for race conditions and edge cases. Frontends such as 66, from the Obarun project, wrap s6 in friendlier tooling.

Key features

• s6-svscan and s6-supervise for process supervision
• s6-rc for dependency-managed services, one-shot jobs and bundles, with live updates
• s6-linux-init to handle boot and shutdown on Linux
• s6-log for rotating logs
• A readiness notification mechanism, so dependents wait until a service signals that it is ready
• execline, an optional scripting language that skips runtime parsing
• Thorough documentation on skarnet.org

Pros

• Precise, fast and one of the most reliable supervisors available.
• Real dependency handling through s6-rc.
• A natural fit for containers, where s6-overlay is a popular choice.
• Detailed documentation for anyone willing to read it.
• A lean PID 1 with nothing extra in it.

Cons

• Steep learning curve. Execline and the s6-rc compile step take time to absorb.
• Several packages must be fitted together, so setup takes more work than systemd or OpenRC.
• Few distros offer it out of the box. Artix is the main one.
• A small community means fewer ready-made service definitions.
• No timers or sandboxing layer.

Best for: containers, embedded systems, minimalists and admins who value correctness over convenience.

Used by: Artix Linux (option), Obarun and many Docker images through s6-overlay.

5. dinit: systemd-Style Dependencies in a Small Package

dinit is a newer service manager and init written in C++ by Davin McCall. It aims at the middle ground: real dependency handling and supervision like systemd, with a much smaller footprint and plain config files. Chimera Linux uses it by default, and Artix offers it as a choice.

Key features

• Service descriptions as simple key = value files
• Hard, soft and milestone dependencies through depends-on, waits-for and depends-ms
• Service types for processes, background processes, scripted jobs, internal services and triggered services
• Automatic restart, socket activation and cgroup support
• dinitctl to control services and dinit-check to lint configs
• A user-level instance for per-user services, with turnstile handling login sessions

Pros

• systemd-style dependency handling at a fraction of the size.
• Readable config that feels familiar if you know unit files.
• No D-Bus requirement.
• Actively developed and gaining distro adoption.

Cons

• Younger and less proven than systemd, OpenRC or runit.
• Few distros ship it, so you often write your own service files.
• No timers or sandboxing layer.
• User services rely on extra tools such as turnstile.

Best for: people who want a lighter system without giving up dependency handling.

Used by: Chimera Linux, with an option on Artix.

6. SysVinit: The Classic Everyone Learned First

SysVinit powered Linux distros for most of their history. It reads /etc/inittab, switches between numbered runlevels and runs shell scripts from /etc/init.d through symlinks in the /etc/rc?.d directories. Debian added dependency-based ordering through LSB headers in Debian 6 (2011), but the core design stayed script-driven and mostly sequential.

Key features

• Runlevels: 0 halts, 1 is single-user, 2 to 5 are multi-user and 6 reboots
• /etc/inittab sets the default runlevel and respawns gettys
• Scripts in /etc/init.d that accept start, stop, restart and status
• Helpers such as service and update-rc.d (Debian family) or chkconfig (Red Hat family)
• Small C binaries and no long-running daemons beyond init itself

Pros

• Easy to understand. Everything is a shell script you can read.
• Predictable and battle-tested over decades.
• Tiny footprint, with no need for cgroups or D-Bus.
• Excellent for learning how Linux boots.

Cons

• Sequential by default, so boot is slower.
• No real supervision beyond inittab respawn.
• Scripts repeat the same boilerplate, often 40 or more lines for a job systemd handles in five.
• No sandboxing, resource limits or on-demand activation.
• A growing amount of software ships only systemd units, so you write the scripts yourself.
• Development is in maintenance mode.

Best for: legacy systems, Devuan users and anyone who wants a boot process with nothing hidden.

Used by: Devuan (default) and the SysVinit editions of MX Linux. Slackware uses the SysVinit binary with BSD-style rc scripts.

7. BusyBox init: The Tiny Embedded Workhorse

BusyBox bundles hundreds of Unix tools into one small binary, and init is one of them. It reads a simplified /etc/inittab and runs commands at boot, on shutdown and whenever a process exits. You find it in many routers and IoT devices, initramfs images, Buildroot builds and Alpine Linux, where it acts as PID 1 and hands service management to OpenRC.

A complete inittab can be this short:

::sysinit:/etc/init.d/rcS
::respawn:/sbin/getty -L 115200 ttyS0 vt100
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r

Key features

• Simplified inittab actions such as sysinit, respawn, askfirst, ctrlaltdel and shutdown
• Signal handling and zombie reaping
• No separate install, since it lives inside the BusyBox binary

Pros

• Tiny and dependency-free.
• Easy to audit and predictable.
• Pairs well with OpenRC when you need real service management.

Cons

• No dependency handling.
• Respawn is the only form of supervision.
• You write all service logic in shell.
• Not suited to general-purpose desktops.

Best for: embedded devices, initramfs images and minimal containers.

Used by: Alpine Linux (as PID 1 alongside OpenRC), Buildroot-based systems and many routers and IoT devices.

8. GNU Shepherd: Services Written in Scheme

GNU Shepherd is the init and service manager of GNU Guix System. It is written in Guile Scheme, so you describe services in Scheme instead of shell or INI files. It reached version 1.0 in late 2024. Shepherd runs as PID 1 on Guix System and also manages user services under Guix Home.

Key features

• Services defined as Scheme objects, with dependencies and supervision built in
• The herd command to start, stop and inspect services
• Arbitrary Guile code available inside service definitions
• System-level and user-level service management
• Tight integration with Guix’s declarative configuration and rollbacks

Pros

• Configuration is real code, so complex services stay manageable.
• Declarative and reproducible when paired with Guix.
• Dependencies and supervision are built in.
• Handles both system and user services.

Cons

• You need to know some Scheme.
• It is closely tied to Guix.
• The community is small.
• The Guile runtime uses more memory than C-based inits.

Best for: Guix System users and people who like declarative, reproducible setups.

Used by: GNU Guix System.

Other init systems you may run into

• Upstart. Canonical’s event-driven init. Ubuntu used it until the switch to systemd in 15.04, and RHEL 6 shipped it too. It is effectively abandoned, so treat it as history.
• procd. The init and process manager in OpenWrt, built for routers.
• Finit. A small init for embedded Linux with service supervision and simple config.
• tini and dumb-init. Not full init systems. These are tiny PID 1 programs for containers that forward signals and reap zombie processes. Docker’s --init flag uses tini.
• Android init. Android uses its own init that reads .rc files. You will never swap it, but it shows how common custom inits are outside the desktop.

What a Service Looks Like in Each Init System

Here is the same job in four init systems: run a custom daemon and restart it if it crashes. The style differences say a lot about each design.

systemd

Save this as /etc/systemd/system/myapp.service, then run systemctl enable --now myapp.

[Unit]
Description=My app
After=network.target

[Service]
ExecStart=/usr/local/bin/myapp
Restart=on-failure

[Install]
WantedBy=multi-user.target

OpenRC

Save this as /etc/init.d/myapp, make it executable, then run rc-update add myapp default.

#!/sbin/openrc-run

description="My app"
command="/usr/local/bin/myapp"
supervisor="supervise-daemon"

depend() {
    need net
}

runit

Create /etc/sv/myapp/run, make it executable, then symlink the directory into the service directory. On Void that is ln -s /etc/sv/myapp /var/service/.

#!/bin/sh
exec /usr/local/bin/myapp 2>&1

dinit

Save this as /etc/dinit.d/myapp, then enable it with dinitctl enable myapp.

type = process
command = /usr/local/bin/myapp
restart = true

The rest follow their own patterns. SysVinit needs a full init script for the same job, usually 40 or more lines of shell that handle start, stop, status and PID files. s6-rc uses a service directory holding a type file that contains the word longrun, an executable run script and an optional dependencies.d directory with one empty file per dependency. BusyBox init needs a single respawn line in /etc/inittab.

Why You Might Want to Change Your Default Init System

Most people have no strong reason to replace systemd. Some do, and their reasons tend to be practical.

Reasons that hold up

• Smaller footprint. A minimal runit or s6 setup uses noticeably less memory than a full systemd stack. On a modern desktop the gap disappears into the noise. When The Register ran the systemd and SysVinit editions of MX Linux 25 side by side in virtual machines, the only difference it noticed was about 50 MB less idle RAM on the SysVinit one. On an old laptop, a Raspberry Pi, a small VPS or a router, that matters more.
• A boot process you can read. With shell scripts and service directories, you can trace a boot from first line to last. When a service refuses to start, adding an echo is a legitimate debugging method.
• Fewer bundled components. Alternatives leave logging, networking, DNS and scheduling to separate tools you pick yourself, such as rsyslog, dhcpcd, iwd and cron. Some people prefer plain-text logs and one tool per job.
• Quick boots on lean systems. Boot time is mostly firmware, kernel and the services you enable. On a trimmed install a light init can reach a login prompt in seconds. On a full desktop with the same services enabled, the gap is small.
• A better fit for containers and embedded devices. A container usually runs one main process, and a router has little memory to spare. s6, BusyBox init and tini suit those jobs better than a full service manager.
• A distro built around your choice. Void, Alpine, Gentoo, Artix, Chimera and Devuan are designed around non-systemd inits. Their packages, docs and communities assume your choice, which saves you from fighting the system.
• Learning value. Running a distro with a different init forces you to learn how services start, and that knowledge carries over to every Linux system you touch.

When switching is a bad idea

• You want a desktop that works out of the box. GNOME depends on logind for session management, so systemd-free setups need elogind. It works, but you become the integrator.
• You rely on software that requires systemd. Snap packages are the usual example. Check anything critical before you move.
• You run production servers. Vendors, support contracts and team habits all assume systemd.
• You expect a dramatic speedup. On a full desktop the difference is usually small.
• It is your only working machine. Test in a VM or on a spare drive first.

What you replace when you leave systemd

Moving off systemd means swapping out the pieces it bundles. Expect to cover these:

• Login and session management: use elogind or seatd. Wayland compositors and most desktops need one of them.
• Logging: use rsyslog, syslog-ng or socklog instead of journald.
• Scheduled jobs: use cron or a similar scheduler in place of timer units.
• Networking and DNS: use NetworkManager, dhcpcd, iwd or ConnMan instead of networkd and resolved.
• Device management: use eudev or mdevd instead of systemd-udevd.
• Per-user services: use turnstile with dinit, runit or s6 if you want user-level services.

How to switch without wrecking your system

1. Try it in a VM or live ISO first. Devuan, Void, Artix, Alpine and Chimera all publish install images.
2. Pick a distro built around your target init instead of converting an existing install. It is far less work.
3. If you must convert, back up and follow the distro’s own documentation. Gentoo documents switching between OpenRC and systemd through profiles, and Devuan documents a path from Debian.
4. Replace logind with elogind or seatd if your desktop or Wayland compositor needs session management.
5. Port your services. Unit files do not carry over, so plan to write scripts or service definitions for each daemon you run.
6. Keep a fallback. A second boot entry, or the init= kernel parameter, lets you boot a different init if the first one fails.

Linux Distros Without systemd

Debian, Ubuntu, Fedora, RHEL, Arch and openSUSE all ship systemd. If you want something else, these distros are built around it:

• Devuan: A Debian fork started over the systemd decision. SysVinit is the default, with OpenRC and runit as install options.
• Void Linux: An independent rolling release distro built around runit, available with glibc or musl.
• Alpine Linux: A tiny musl-based distro that pairs BusyBox with OpenRC. Popular for containers.
• Gentoo: A source-based distro with OpenRC by default and documented systemd profiles if you change your mind.
• Artix Linux: Arch-based, with your choice of OpenRC, runit, s6 or dinit.
• Chimera Linux: An independent distro that pairs dinit with musl and LLVM.
• MX Linux: Debian-based. MX 25 defaults to systemd, and separate SysVinit editions of Xfce and Fluxbox remain available.
• antiX: A lightweight, systemd-free Debian-based distro with several init choices, including runit, dinit and s6.
• Slackware: The oldest surviving distro, with BSD-style init scripts.
• GNU Guix System: A declarative distro that uses Shepherd.

How to Choose the Right Init System

• You want it to work and you want help when it does not: use systemd.
• You like shell scripts and want a lighter system: use OpenRC through Gentoo, Alpine or Artix.
• You want the simplest supervised system possible: use runit through Void.
• You want rigor, small containers or minimal images: use s6.
• You want systemd-style dependencies in a small package: use dinit through Chimera or Artix.
• You want a classic, readable boot on a Debian base: use SysVinit through Devuan or the MX Linux SysVinit editions.
• You are building an embedded device: start with BusyBox init, then add OpenRC, Finit or procd as service needs grow.
• You live in Guix: you already use Shepherd.

Stay on systemd until it causes a concrete problem for you. A 256 MB VM that keeps running out of memory is a good reason to move. A forum argument is not.

The Short Version

There is no single best init system. systemd wins on features, tooling and support, which is why nearly every major distro ships it. OpenRC, runit, s6 and dinit win on size, simplicity and control, which is why people keep building distros around them. SysVinit, BusyBox init and Shepherd serve smaller groups well.

Pick based on the machine and the job, test in a VM, and switch only for a reason you can name. Running something other than systemd? Tell us what you run and why in the comments.

Frequently Asked Questions About Linux Init Systems

What is an init system in Linux?

An init system is the first process the kernel starts, running as PID 1. It brings the system up at boot, starts and manages services, adopts orphaned processes and handles shutdown. systemd, OpenRC, runit, s6, dinit and SysVinit are the best-known examples.

What is the most popular Linux init system?

systemd. It is the default on Debian, Ubuntu, Fedora, RHEL, Arch, openSUSE and most other mainstream distros.

Is systemd the best init system?

For most people it is the most practical choice, with the widest support, the most features and the best tooling. Best depends on your goals, though. If you want a smaller footprint, readable scripts or a systemd-free distro, OpenRC, runit, s6 or dinit fit better.

What is the lightest Linux init system?

BusyBox init, runit and s6 are among the smallest. dinit and OpenRC are also light. On a full desktop the practical difference is small, because the services you enable matter more than the init itself. It counts most on embedded devices, containers and old hardware.

What is the difference between SysVinit and systemd?

SysVinit starts services mostly in sequence with shell scripts and runlevels, and does little to supervise them. systemd uses declarative unit files, starts services in parallel based on dependencies, tracks processes with cgroups and restarts failed services automatically. systemd 260 also removed support for running old SysV init scripts.

Can I replace systemd on my current Linux install?

Sometimes. Gentoo documents switching between OpenRC and systemd, and Devuan documents a path from Debian. On most other distros the change is fragile, because packages, desktop environments and services expect systemd. A fresh install of a distro built around your target init is safer. Test in a VM first.

Which Linux distros do not use systemd?

Devuan, Void Linux, Alpine Linux, Gentoo, Artix Linux, Chimera Linux, antiX, Slackware and GNU Guix System all run without systemd by default. MX Linux still offers SysVinit editions, although its main editions now use systemd.

Is OpenRC better than systemd?

OpenRC is simpler and lighter, and it uses plain shell scripts. systemd offers more features, including timers, socket activation, sandboxing and deeper tooling. Neither wins in every case, so pick the one that matches what you value more, simplicity or features.

Do Docker containers need an init system?

Usually not a full one. A container runs one main process, but an ordinary application running as PID 1 often fails to reap zombie processes or forward signals correctly. Docker’s --init flag adds tini to handle this, and s6-overlay suits containers that run several processes.

How do I check which init system my Linux machine uses?

Run ps -p 1 -o comm= to see the name of PID 1. If it prints init, run readlink -f /sbin/init to see whether it points to the BusyBox binary or a standalone SysVinit binary.

Is Upstart still used?

No. Ubuntu replaced Upstart with systemd in 15.04, and Upstart has been effectively abandoned since. It is only worth knowing as history.