How do I set the run target and turn off services on a non running installation ?

[linux guy]

I have a non booting installation that I need to get running.  I would like
to know how to change the run target to the command line and disable
several services that are causing issues during the boot process.

How does one manually change the run target on a non booting installation
?  What do I edit ?  Because my installation doesn't boot, I can't run
systemctl, so I must edit the link manually.

How does one manually disable services so they don't start during the boot
process ?  Because my installation doesn't boot, I can't run systemctl, so
I must edit the configuration manually.

Thanks

[Patrick O'Callaghan]

On Mon, 2017-03-06 at 10:37 -0700, linux guy wrote:
> I have a non booting installation that I need to get running.  I would like
> to know how to change the run target to the command line and disable
> several services that are causing issues during the boot process.
>
> How does one manually change the run target on a non booting installation
> ?  What do I edit ?  Because my installation doesn't boot, I can't run
> systemctl, so I must edit the link manually.
> [...]

https://www.linux.com/learn/how-rescue-non-booting-grub-2-linux

poc

[Eddie G. O'Connor Jr.]

On 03/06/2017 12:37 PM, linux guy wrote:
> I have a non booting installation that I need to get running.  I would 
> like to know how to change the run target to the command line and 
> disable several services that are causing issues during the boot process.
>
> How does one manually change the run target on a non booting 
> installation ?  What do I edit ?  Because my installation doesn't 
> boot, I can't run systemctl, so I must edit the link manually.
>
> How does one manually disable services so they don't start during the 
> boot process ?  Because my installation doesn't boot, I can't run 
> systemctl, so I must edit the configuration manually.
>
> Thanks
>
> users mailing list -- [e-mail]
> To unsubscribe send an email to [e-mail]

I'm no expert but i think you'd check the /boot.config file?...(Correct 
me if I'm wrong community!) Either there or the /grub.config file, to 
set things the way you want upon boot. This way you'd at least be able 
to get into the system and then go forward from there. (I wonder if just 
copying the bits and pieces from the drive and placing them 
elsewhere....then booting from the new drive - network location, 
wouldn't be a better option?) just my 2 cents

EGO II

[linux guy]

​I'm doing this on an RPi 3 running F25.  It boots using extLinux, not
grub2, from what I can tell.   There are grub and grub2 files in /boot, but
it doesn't seem to use them.

[linux guy]

​I've got it booting to a command prompt by adding 'init=/bin/bash' to the
kernel parameters, but it shuts off USB and other services before it gets
there, thus leaving me with no keyboard.

[linux guy]

There is a grub.conf file in /boot/grub, but it isn't current to the
installation and doesn't appear to be used.   It references a kernel that
isn't installed.

It appears the boot process is controlled by /boot/extlinux/extlinux.conf.
That file is set up similar to a grub.conf file.

There is no conf/config file in /boot.

[Jeroen Mathon]

On Monday, March 6, 2017 6:37:32 PM CET linux guy wrote:
> I have a non booting installation that I need to get running.  I would like
> to know how to change the run target to the command line and disable
> several services that are causing issues during the boot process.
>
> How does one manually change the run target on a non booting installation
> ?  What do I edit ?  Because my installation doesn't boot, I can't run
> systemctl, so I must edit the link manually.
>
> How does one manually disable services so they don't start during the boot
> process ?  Because my installation doesn't boot, I can't run systemctl, so
> I must edit the configuration manually.
>
> Thanks

Hey.

During the bootloader process you can define the runlevel to run your kernel 
at.

By setting it to 3 you will be able to boot into a cmdline with network 
functionality and minimal services.

See: https://www.centos.org/docs/5/html/Installation_Guide-en-US/s1-grub-runlevel... for more information.

[linux guy]

I got the installation booting on my RPi3 again. I couldn't update it with
dnf update because the update was simply too large to run. I might try
again in the near future.

Here are some things that I learned in this effort.

1) RPi3 boots with extlinux, not grub or grub2.

2) To change the kernel boot parameters, edit /boot/extlinux/extlinux.conf

3) You can set the run level via the kernel parameters.

- add "systemd.unit=runlevel1.target" to the append line in the kernel
   parameters, for example

https://docs.fedoraproject.org/en-US/Fedora/19/html/Installation_Guide/s1-gr...

https://fedoraproject.org/wiki/SysVinit_to_Systemd_Cheatsheet

4) To disable various services, remove service.service from the
target.wants folder for the target you are using. Each target has its own
wants folder ! If you change run levels, you'll have to re enable various
services.

For example, in the /usr/lib/systemd/system/multi-user.target.wants

[me@localhost multi-user.target.wants]$ ls -al total 28 drwxr-xr-x. 3 root
root 4096 Mar 6 15:31 . drwxr-xr-x. 29 root root 20480 Jan 31 11:59 ..
lrwxrwxrwx. 1 root root 15 Nov 29 07:24 dbus.service -> ../dbus.service
lrwxrwxrwx. 1 root root 15 Jan 16 06:00 getty.target -> ../getty.target
drwxr-xr-x. 2 root root 4096 Mar 6 15:31 hidden lrwxrwxrwx. 1 root root 24
Jun 20 2016 plymouth-quit.service -> ../plymouth-quit.service lrwxrwxrwx. 1
root root 29 Jun 20 2016 plymouth-quit-wait.service ->
../plymouth-quit-wait.service lrwxrwxrwx. 1 root root 33 Jan 16 06:00
systemd-ask-password-wall.path -> ../systemd-ask-password-wall.path
lrwxrwxrwx. 1 root root 39 Jan 16 06:00
systemd-update-utmp-runlevel.service ->
../systemd-update-utmp-runlevel.service lrwxrwxrwx. 1 root root 32 Jan 16
06:00 systemd-user-sessions.service -> ../systemd-user-sessions.service

Hint: to disable a service, make a folder called hidden and move the
service to that folder.

5) To start raw networking manually, do the following:

With a dynamic IP $ ifconfig eth0 up $ sudo dhclient eth0

With a static IP To set IP address you want (for example 192.168.0.1) type:
$ ifconfig eth0 192.168.0.1 netmask 255.255.255.0 up $ route add default gw
GATEWAY-IP eth0

If you want to use Network Manager:

systemctl stop NetworkManager.service systemctl disable
NetworkManager.service

Then you enable the network service in a similar fashion. systemctl enable
network.service systemctl start network.service

Network Manager Command Line Interface documentation
https://fedoraproject.org/wiki/Networking/CLI

http://serverfault.com/questions/21475/starting-network-connection-from-ubun...

If you get a message about resolv.conf not being found, it is supposed to
get set to something at boot time. Create a fake one or run NetworkManager
to get it to create one.

/run/resolvconf/resolv.conf is a symbolic link that should point to a real
file

https://ubuntuforums.org/showthread.php?t=2068299

Hope this helps someone.
​