[lclarkmichalek]

If you are on a systemd system, you can check your version with

    $ init --version
    systemd 231
    +PAM +AUDIT +SELINUX +IMA -APPARMOR +SMACK -SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT -GNUTLS -ACL +XZ -LZ4 +SECCOMP +BLKID -ELFUTILS +KMOD -IDN

[mhotchen]

Despite being in the man page, the flag --version didn't work for me on Ubuntu 16.04 (various different installations):

    $ init --version
    init: unrecognised option '--version'

systemd --version works though:

    $ systemd --version
    systemd 229

[ilkkao]

systemctl --version on Fedora

[tonyhb]

Same thing on Nix. Thanks.

[krylon]

Same on Debian Jessie.

EDIT: And on openSUSE Tumbleweed

[Outpox]

Same on Mint 18

[JdeBP]

On a systemd operating system there may or may not be a program called "init" and it may or may not be an alias for a systemd program. (One's operating system could be one of the ones that just invokes "/lib/systemd/systemd" directly without an "init" at all; or "init" could be Upstart or van Smoorenburg init or the nosh system manager; and of course just running unadorned "init" assumes that "/sbin" is on an unprivileged user's PATH.)

The best command to invoke here is either "systemctl" or "systemd".