The Story Behind ‘init’ and ‘systemd’: Why ‘init’ Needed to be Replaced with ‘systemd’ in Linux

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57 Responses

  1. Allan says:

    Your history is a bit inaccurate. /sbin/init dates back at least to 3.2 release 4.2, and I’m told it dates back to System 3.1 that was fire-and-forget mailed as a digital tape to Berkeley that started BSD the *BSD variants.

    In fact, on 3.2r4.2 (Open Desktop), /etc/inittab was an aggregation of /etc/init.d/*, which is where the idea came from for Apache to read conf.d as a file-tree-walk in Apache-1.3.13 on-th-fly, which is now copied by everyone.

    /sbin/init was originally intended to restart printer services; it later was reused to restart vt100 terminal restarts when they died. The expansion to /etc/rc.d/ crap was done so that configs could be “added” as files when new software packages are installed (3.2r4.2 would “recompile” the config, svr5 — Unixware, Solaris — would read them in-place). Even using it to restart TCP services in general was seen as a stretch but /sbin/init performed well beyond its design scope.

    So, /sbin/init had very modest roots, was already performing beyond designed intents, but did its job very well. I’m not a fan of the systemd “do all the things” approach, but sometimes we need to make the bold step forward, try to iterate to improve, and see whether that gets us a benefit or a rollback.

  2. Geoff Harrison says:

    sorry, but systemd is an abomination, and so is upstart, frankly. I don’t see why we replace the one thing that SysV got right.

    -mandrake (if you’ve been in the Linux world that long, yes, that one)

  3. Samuel says:

    Systemd was a mistake to begin with. Change is coming (sinit, s6, openrc, shepherd, runit).
    https://devuan.org/os/debian-fork/

    You can add to systemd bottlenecks:
    bugs uncovered day in, day out (you remember about the “tweeter” thing? is that the kind of thing you would expect from /sbin/init?)

    when your root device fails, any already-opened session is rendered useless (can’t access systemd logs, can’t debug, can’t reboot, that’s something you used being able to do, when these used to be separate components, one might have broken without bringing down everything)

    AFAIU: there isn’t a single developer with a full visual on the whole project ramifications/understanding of what’s going on, what could go wrong.
    binary logs => logs corruption.

    Listing “low memory footprint” as a feature doesn’t make any sense: what are we comparing? have you looked at init?

    Saying systemd isn’t POSIX compliant is a cute euphemism. From day one: systemd didn’t comply with Unix philosophy. That should have been a red light, and I blame Red Hat here.

  4. WhatConnor says:

    easy extensible startup script row? what drugs are you on?
    have you ever written a service script for either daemons?

  5. Aman Raj says:

    Nice article brief and informative .
    Thanks , keep posting the similar things

  6. Reddy says:

    Excellent Article

  7. Lawrence says:

    Why no one start something to opposite it and use init instead. I’m new to Linux but I agree with the term no broken don’t fix it. In fact a lot of people will be able to have a stable and effective system if the system stop changing dramatically.

    More contributors and newcomer like myself would enjoy Linux centos more. Please don’t end up like ms window os.

    • Jack says:

      Henry Ford said it best:

      – “If I’d of given the people what they wanted, they would’ve got faster horses”

      Same applies here.

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