<SOLVED> Terminal commands "shutdown now" and "reboot now"

[senjoz]

Terminal command shutdown now shuts the computer down. Terminal command reboot now should reboot the computer. But this command requires sudo elevated privileges. To reboot from terminal one must use sudo reboot now.

Why rebooting requires elevated privileges?

Regards, Jože

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~$ inxi -Fxxxrz
System:
  Kernel: 6.1.0-1004-oem arch: x86_64 bits: 64 compiler: N/A Desktop: Cinnamon
    v: 5.6.7 tk: GTK v: 3.24.33 wm: muffin vt: 1 dm: startx
    Distro: Linux Mint 21.1 Vera base: Ubuntu 22.04 jammy
Machine:
  Type: Laptop System: FUJITSU CLIENT product: LIFEBOOK A3511 v: N/A
    serial: <superuser required> Chassis: type: 10 serial: <superuser required>
  Mobo: FUJITSU CLIENT model: FJNBB73 v: EQAA023236
    serial: <superuser required> UEFI: FUJITSU CLIENT v: Version 1.09
    date: 02/18/2022
Battery:
  ID-1: BAT1 charge: 33.4 Wh (79.5%) condition: 42.0/45.0 Wh (93.2%)
    volts: 11.8 min: 10.8 model: PAC CP753347-01 type: Li-ion serial: <filter>
    status: not charging
CPU:
  Info: dual core model: 11th Gen Intel Core i3-1115G4 bits: 64 type: MT MCP
    smt: enabled arch: Tiger Lake rev: 1 cache: L1: 160 KiB L2: 2.5 MiB
    L3: 6 MiB
  Speed (MHz): avg: 2367 high: 3115 min/max: 400/4100 cores: 1: 3115 2: 1999
    3: 1357 4: 3000 bogomips: 23961
  Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Graphics:
  Device-1: Intel vendor: Fujitsu Client driver: i915 v: kernel arch: Gen-12.1
    ports: active: eDP-1 empty: DP-1,HDMI-A-1,HDMI-A-2 bus-ID: 00:02.0
    chip-ID: 8086:9a78 class-ID: 0300
  Device-2: Chicony FJ Camera type: USB driver: uvcvideo bus-ID: 3-7:3
    chip-ID: 04f2:b6a0 class-ID: 0e02
  Display: server: X.Org v: 1.21.1.3 with: Xwayland v: 22.1.1 driver: X:
    loaded: modesetting unloaded: fbdev,vesa dri: iris gpu: i915 display-ID: :0
    screens: 1
  Screen-1: 0 s-res: 1920x1080 s-dpi: 96 s-size: 508x285mm (20.00x11.22")
    s-diag: 582mm (22.93")
  Monitor-1: eDP-1 model: BOE Display 0x0700 res: 1920x1080 hz: 60 dpi: 142
    size: 344x194mm (13.54x7.64") diag: 395mm (15.5") modes: 1920x1080
  API: OpenGL v: 4.6 Mesa 22.2.5 renderer: Mesa Intel UHD Graphics (TGL GT2)
    direct render: Yes
Audio:
  Device-1: Intel Tiger Lake-LP Smart Sound Audio vendor: Fujitsu Client
    driver: sof-audio-pci-intel-tgl bus-ID: 00:1f.3 chip-ID: 8086:a0c8
    class-ID: 0401
  Sound API: ALSA v: k6.1.0-1004-oem running: yes
  Sound Server-1: PulseAudio v: 15.99.1 running: yes
  Sound Server-2: PipeWire v: 0.3.48 running: yes
Network:
  Device-1: Intel Wi-Fi 6 AX201 driver: iwlwifi v: kernel bus-ID: 00:14.3
    chip-ID: 8086:a0f0 class-ID: 0280
  IF: wlp0s20f3 state: up mac: <filter>
  Device-2: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet
    vendor: Fujitsu Client driver: r8169 v: kernel pcie: speed: 2.5 GT/s
    lanes: 1 port: 3000 bus-ID: 07:00.0 chip-ID: 10ec:8168 class-ID: 0200
  IF: enp7s0 state: down mac: <filter>
Drives:
  Local Storage: total: 238.47 GiB used: 12.28 GiB (5.1%)
  ID-1: /dev/nvme0n1 vendor: Samsung model: MZVLQ256HAJD-00007
    size: 238.47 GiB speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter>
    rev: FXV7202Q temp: 22.9 C scheme: GPT
Partition:
  ID-1: / size: 62.44 GiB used: 12.24 GiB (19.6%) fs: ext4 dev: /dev/nvme0n1p4
  ID-2: /boot/efi size: 511 MiB used: 35.2 MiB (6.9%) fs: vfat
    dev: /dev/nvme0n1p1
Swap:
  ID-1: swap-1 type: file size: 2 GiB used: 0 KiB (0.0%) priority: -2
    file: /swapfile
Sensors:
  System Temperatures: cpu: 50.0 C mobo: N/A
  Fan Speeds (RPM): N/A
Repos:
  Packages: pm: dpkg pkgs: 2082
  No active apt repos in: /etc/apt/sources.list
  Active apt repos in: /etc/apt/sources.list.d/official-package-repositories.list
    1: deb http://packages.linuxmint.com vera main upstream import backport
    2: deb http://archive.ubuntu.com/ubuntu jammy main restricted universe multiverse
    3: deb http://archive.ubuntu.com/ubuntu jammy-updates main restricted universe multiverse
    4: deb http://archive.ubuntu.com/ubuntu jammy-backports main restricted universe multiverse
    5: deb http://security.ubuntu.com/ubuntu/ jammy-security main restricted universe multiverse
Info:
  Processes: 228 Uptime: 12m wakeups: 597 Memory: 15.3 GiB
  used: 2.08 GiB (13.6%) Init: systemd v: 249 target: multi-user (3)
  default: multi-user Compilers: gcc: 11.3.0 alt: 11/12 Shell: Bash v: 5.1.16
  running-in: gnome-terminal inxi: 3.3.24

[coffee412]

Because they do not want me logging into AT&T email servers and shutting them down or rebooting them.

John works at a company and has to constantly log in to a server and restart a program that likes to freeze up. This program provides services for 100 employees. He is under the gun to get this done as quick as possible. These 100 employee's are all working on their spreadsheets that contain very important information about the company. John is frustrated and feeling rushed. So, To kill the program he rushes and enters

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Reboot

by mistake.

[senjoz]

Thank you for your comment, coffee412!

Because they do not want me logging into AT&T email servers and shutting them down or rebooting them.

But why does shutdown work without sudo? Why the difference?

[coffee412]

In my test VM, It shows everyone has permission to shutdown the computer. Makes sense kinda as its a desktop computer and you can shut it down from the main menu as the current logged in user. I think on debian (have to check) that probably might be different in a server environment.

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coffee@MINT20-TEST:/sbin$ ls -l shutdown
lrwxrwxrwx 1 root root 14 Apr 21  2022 shutdown -> /bin/systemctl

I had a friend in England once (long story) and he was showing me how great windows was over linux. He had setup voice control and had me on skype. He is showing how he can start programs and such and then he said "I bet you cant beat that?".

I yelled in the mic "Shutdown now".

His skype connected disconnected and he went off line.

[all41]

Also see for systemd:
systemctl poweroff
and
systemctl reboot
how to in:
man systemctl

These also run without escalated privilege

[vimes666]

FYI: in LMDE5 reboot works without sudo.

[all41]

FYI: in LMDE5 reboot works without sudo.

Funny because some popular distro terminals require sudo to reboot--but don't ask for the password to prove
sudo privilege

[senjoz]

FYI: in LMDE5 reboot works without sudo.

My LMDE5 installation requires sudo for terminal command reboot now. Command shutdown now works without sudo. The same is in Manjaro. PCLinuxOS behaves differently, it is an SysVinit system.

[vimes666]

FYI: in LMDE5 reboot works without sudo.

My LMDE5 installation requires sudo for terminal command reboot now.

And if you do reboot without now?

[senjoz]

Interesting, terminal command reboot, without now, works without sudo. That is true for LM20.3, LMDE5 and Manjaro.

[vimes666]

I am more surprised that the now argument actually seems to do something as it is not mentioned in the manual:

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man reboot

[rene]

The privilege stuff is a matter of...

As per

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$ ls -l $(which reboot shutdown)
lrwxrwxrwx 1 root root 14 feb  4 09:19 /usr/sbin/reboot -> /bin/systemctl
lrwxrwxrwx 1 root root 14 feb  4 09:19 /usr/sbin/shutdown -> /bin/systemctl

you find that the current reboot and shutdown are systemd implementations, and as such, authenticate via polkit. Specifically you in /usr/share/polkit-1/actions/org.freedesktop.login1.policy find for org.freedesktop.login1.power-off and org.freedesktop.login1.reboot as requested by shutdown and reboot:

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<defaults>
	<allow_any>auth_admin_keep</allow_any>
	<allow_inactive>auth_admin_keep</allow_inactive>
	<allow_active>yes</allow_active>
</defaults>

with then the "allow_active" part saying that both shutdown and reboot is allowed for clients in active sessions on local consoles. I.e., that same user that could hit the power or reboot button on the case anyway (and if you hot-glued those buttons feel free to change that policy with an override in /etc/polkit-1). The permission does not extend to e.g. someone logged in over ssh or in fact to a not physically logged in user.

I see that the "now" thing is only a matter of not being allowed to write the reboot parameter file:

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$ reboot now
Failed to write reboot parameter file: Permission denied

Yes, bit clumsy perhaps, but assuming that "reboot parameter file" is written to the root directory (haven't in fact a clue), yes, that needs not just org.freedesktop.login1.power-off/reboot. sudo doesn't have the ability to make the distinction between local or otherwise, and between active or otherwise, so can not act similarly -- but if it could've it would've.

[vimes666]

...

Yes, I see now that it says Failed to write reboot parameter file with any string you add to the command.

[LPH_[retired]]

fyi

On Mint 20.3 here. I use

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shutdown -r 0

which reboots the machine immediately with out sudo.
For convenience I created an alias name restart. Works fine.

Must admit I'm not clear on the difference between shutdown -r and reboot command. Other than appearing to be doing the same thing, is there a difference?
Preferred one over the other?
(Apologies not trying to hijack this thread)

[rene]

Must admit I'm not clear on the difference between shutdown -r and reboot command. Other than appearing to be doing the same thing, is there a difference? Preferred one over the other?

Other than shutdown needing/allowing for that timeout argument, no, also shutdown is on current Mint in fact systemctl, and shutdown -r 0 does other than a bit of parsing of said -r 0 and acting on it no other than reboot.

In times not long forgotten -- although I don't myself remember if it was still so in Mint 19 and/or Mint 20 -- shutdown in fact still came from util-linux whereas reboot was already the systemd one so back then there was a difference (even if not really any preferred one) but at least currently, it's all just systemctl:

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$ ls -l $(which shutdown halt reboot)
lrwxrwxrwx 1 root root 14 feb  4 09:19 /usr/sbin/halt -> /bin/systemctl
lrwxrwxrwx 1 root root 14 feb  4 09:19 /usr/sbin/reboot -> /bin/systemctl
lrwxrwxrwx 1 root root 14 feb  4 09:19 /usr/sbin/shutdown -> /bin/systemctl

[senjoz]

Thank you, rene, for your detailed explanation. Obviously the argument now is not appropriate for the reboot command and sudo is only some kind of workaround for the wrong command.