RH134 - CH13 - Controlling and Troubleshooting RHEL boot process

1. RHEL 7 booting process. -> page 266, 277

2. To Poweroff machine or reboot it:

[root@server0 ~]# systemctl poweroff
[root@server0 ~]# systemctl reboot

3. 'poweroff' and 'reboot' commands are still there but has symbolic links to the new command 'systemctl':

[root@server0 ~]# ls -lh /sbin/poweroff 
lrwxrwxrwx. 1 root root 16 May  7  2014 /sbin/poweroff -> ../bin/systemctl

[root@server0 ~]# ls -lh /sbin/reboot 
lrwxrwxrwx. 1 root root 16 May  7  2014 /sbin/reboot -> ../bin/systemctl

4. Defenation of 'systemctl halt' as in pager 267:

[root@server0 ~]# systemctl halt

Result:

You can now Poweroff the machine manually:

[root@server0 ~]# ls -lh /sbin/halt 
lrwxrwxrwx. 1 root root 16 May  7  2014 /sbin/halt -> ../bin/systemctl

5. 'systemd target' dfination -> page 267,268
List current active 'systemd target':

[root@server0 ~]# systemctl list-units --type help
Available unit types:
service
socket
target
device
mount
automount
snapshot
timer
swap
path
slice
scope

[root@server0 ~]# systemctl list-units --type=target 
UNIT                LOAD   ACTIVE SUB    DESCRIPTION
basic.target        loaded active active Basic System
cryptsetup.target   loaded active active Encrypted Volumes
getty.target        loaded active active Login Prompts
graphical.target    loaded active active Graphical Interface
local-fs-pre.target loaded active active Local File Systems (Pre)
local-fs.target     loaded active active Local File Systems
multi-user.target   loaded active active Multi-User System
network.target      loaded active active Network
nfs.target          loaded active active Network File System Server
paths.target        loaded active active Paths
remote-fs.target    loaded active active Remote File Systems
slices.target       loaded active active Slices
sockets.target      loaded active active Sockets
swap.target         loaded active active Swap
sysinit.target      loaded active active System Initialization
timers.target       loaded active active Timers

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

16 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

You can found it also in '/etc/systemd/system' dir:

root@server0 ~]# ls -lh /etc/systemd/system
total 12K
drwxr-xr-x. 2 root root   54 Jul 11  2014 basic.target.wants
drwxr-xr-x. 2 root root   30 Jul 11  2014 bluetooth.target.wants
lrwxrwxrwx. 1 root root   41 Jul 11  2014 dbus-org.bluez.service -> /usr/lib/systemd/system/bluetooth.service
lrwxrwxrwx. 1 root root   41 Jul 11  2014 dbus-org.fedoraproject.FirewallD1.service -> /usr/lib/systemd/system/firewalld.service
lrwxrwxrwx. 1 root root   44 May  7  2014 dbus-org.freedesktop.Avahi.service -> /usr/lib/systemd/system/avahi-daemon.service
lrwxrwxrwx. 1 root root   44 Jul 11  2014 dbus-org.freedesktop.ModemManager1.service -> /usr/lib/systemd/system/ModemManager.service
lrwxrwxrwx. 1 root root   46 May  7  2014 dbus-org.freedesktop.NetworkManager.service -> /usr/lib/systemd/system/NetworkManager.service
lrwxrwxrwx. 1 root root   57 May  7  2014 dbus-org.freedesktop.nm-dispatcher.service -> /usr/lib/systemd/system/NetworkManager-dispatcher.service
lrwxrwxrwx. 1 root root   40 Jul 11  2014 default.target -> /usr/lib/systemd/system/graphical.target
drwxr-xr-x. 2 root root   85 May  7  2014 default.target.wants
lrwxrwxrwx. 1 root root   35 Jul 11  2014 display-manager.service -> /usr/lib/systemd/system/gdm.service
drwxr-xr-x. 2 root root   31 May  7  2014 getty.target.wants
drwxr-xr-x. 2 root root   63 Jul 11  2014 graphical.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 multi-user.target.wants
drwxr-xr-x. 2 root root   29 May  7  2014 nfs.target.wants
drwxr-xr-x. 2 root root   25 Jul 11  2014 printer.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 sockets.target.wants
drwxr-xr-x. 2 root root   35 Jul 11  2014 spice-vdagentd.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 sysinit.target.wants
drwxr-xr-x. 2 root root   83 Jul 11  2014 system-update.target.wants
lrwxrwxrwx. 1 root root    9 May  7  2014 tmp.mount -> /dev/null

List all 'systemd target':

[root@server0 ~]# systemctl list-units --type=target --all
UNIT                   LOAD   ACTIVE   SUB    DESCRIPTION
basic.target           loaded active   active Basic System
cryptsetup.target      loaded active   active Encrypted Volumes
emergency.target       loaded inactive dead   Emergency Mode
final.target           loaded inactive dead   Final Step
getty.target           loaded active   active Login Prompts
graphical.target       loaded active   active Graphical Interface
local-fs-pre.target    loaded active   active Local File Systems (Pre)
local-fs.target        loaded active   active Local File Systems
multi-user.target      loaded active   active Multi-User System
network-online.target  loaded inactive dead   Network is Online
network.target         loaded active   active Network
nfs.target             loaded active   active Network File System Server
nss-lookup.target      loaded inactive dead   Host and Network Name Lookups
nss-user-lookup.target loaded inactive dead   User and Group Name Lookups
paths.target           loaded active   active Paths
remote-fs-pre.target   loaded inactive dead   Remote File Systems (Pre)
remote-fs.target       loaded active   active Remote File Systems
rescue.target          loaded inactive dead   Rescue Mode
shutdown.target        loaded inactive dead   Shutdown
slices.target          loaded active   active Slices
sockets.target         loaded active   active Sockets
swap.target            loaded active   active Swap
sysinit.target         loaded active   active System Initialization
syslog.target          not-found inactive dead   syslog.target
time-sync.target       loaded inactive dead   System Time Synchronized
timers.target          loaded active   active Timers
umount.target          loaded inactive dead   Unmount All Filesystems

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

27 loaded units listed.
To show all installed unit files use 'systemctl list-unit-files'.

IMPORTANT:
Main'systemd target' defination can be found in

[root@server0 ~]# man systemd.special
[root@server0 ~]# man systemd.target

To be reviewed:

[root@server0 ~]# systemctl list-unit-files --type=target 
[root@server0 ~]# systemctl list-unit-files --type=target --all

6. List dependancies of 'systemd target':

[root@server0 ~]# systemctl list-dependencies graphical.target | grep target
graphical.target
└─multi-user.target
  ├─basic.target
  │ ├─paths.target
  │ ├─slices.target
  │ ├─sockets.target
  │ ├─sysinit.target
  │ │ ├─cryptsetup.target
  │ │ ├─local-fs.target
  │ │ └─swap.target
  │ └─timers.target
  ├─getty.target
  ├─nfs.target
  └─remote-fs.target

7. Selecting 'systemd target' at runtime:
Following command is some sort equal to 'init 3':

[root@server0 ~]# systemctl isolate multi-user.target

8. Find default 'systemd target' using 'systemctl get-default' command line or by exploaring '/etc/systemd/system' dir:

[root@server0 ~]# systemctl get-default
graphical.target

[root@server0 ~]# ls -lh /etc/systemd/system
total 12K
drwxr-xr-x. 2 root root   54 Jul 11  2014 basic.target.wants
drwxr-xr-x. 2 root root   30 Jul 11  2014 bluetooth.target.wants
lrwxrwxrwx. 1 root root   41 Jul 11  2014 dbus-org.bluez.service -> /usr/lib/systemd/system/bluetooth.service
lrwxrwxrwx. 1 root root   41 Jul 11  2014 dbus-org.fedoraproject.FirewallD1.service -> /usr/lib/systemd/system/firewalld.service
lrwxrwxrwx. 1 root root   44 May  7  2014 dbus-org.freedesktop.Avahi.service -> /usr/lib/systemd/system/avahi-daemon.service
lrwxrwxrwx. 1 root root   44 Jul 11  2014 dbus-org.freedesktop.ModemManager1.service -> /usr/lib/systemd/system/ModemManager.service
lrwxrwxrwx. 1 root root   46 May  7  2014 dbus-org.freedesktop.NetworkManager.service -> /usr/lib/systemd/system/NetworkManager.service
lrwxrwxrwx. 1 root root   57 May  7  2014 dbus-org.freedesktop.nm-dispatcher.service -> /usr/lib/systemd/system/NetworkManager-dispatcher.service
lrwxrwxrwx. 1 root root   40 Jul 11  2014 default.target -> /usr/lib/systemd/system/graphical.target
drwxr-xr-x. 2 root root   85 May  7  2014 default.target.wants
lrwxrwxrwx. 1 root root   35 Jul 11  2014 display-manager.service -> /usr/lib/systemd/system/gdm.service
drwxr-xr-x. 2 root root   31 May  7  2014 getty.target.wants
drwxr-xr-x. 2 root root   63 Jul 11  2014 graphical.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 multi-user.target.wants
drwxr-xr-x. 2 root root   29 May  7  2014 nfs.target.wants
drwxr-xr-x. 2 root root   25 Jul 11  2014 printer.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 sockets.target.wants
drwxr-xr-x. 2 root root   35 Jul 11  2014 spice-vdagentd.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 sysinit.target.wants
drwxr-xr-x. 2 root root   83 Jul 11  2014 system-update.target.wants
lrwxrwxrwx. 1 root root    9 May  7  2014 tmp.mount -> /dev/null

9. Set Default 'systemd target':

[root@server0 ~]# systemctl  get-default
graphical.target

[root@server0 ~]# ls -lh /etc/systemd/system total 12K drwxr-xr-x. 2 root root 54 Jul 11 2014 basic.target.wants drwxr-xr-x. 2 root root 30 Jul 11 2014 bluetooth.target.wants lrwxrwxrwx. 1 root root 41 Jul 11 2014 dbus-org.bluez.service -> /usr/lib/systemd/system/bluetooth.service lrwxrwxrwx. 1 root root 41 Jul 11 2014 dbus-org.fedoraproject.FirewallD1.service -> /usr/lib/systemd/system/firewalld.service lrwxrwxrwx. 1 root root 44 May 7 2014 dbus-org.freedesktop.Avahi.service -> /usr/lib/systemd/system/avahi-daemon.service lrwxrwxrwx. 1 root root 44 Jul 11 2014 dbus-org.freedesktop.ModemManager1.service -> /usr/lib/systemd/system/ModemManager.service lrwxrwxrwx. 1 root root 46 May 7 2014 dbus-org.freedesktop.NetworkManager.service -> /usr/lib/systemd/system/NetworkManager.service lrwxrwxrwx. 1 root root 57 May 7 2014 dbus-org.freedesktop.nm-dispatcher.service -> /usr/lib/systemd/system/NetworkManager-dispatcher.service lrwxrwxrwx. 1 root root 40 Jul 11 2014 default.target -> /usr/lib/systemd/system/graphical.target drwxr-xr-x. 2 root root 85 May 7 2014 default.target.wants lrwxrwxrwx. 1 root root 35 Jul 11 2014 display-manager.service -> /usr/lib/systemd/system/gdm.service drwxr-xr-x. 2 root root 31 May 7 2014 getty.target.wants drwxr-xr-x. 2 root root 63 Jul 11 2014 graphical.target.wants drwxr-xr-x. 2 root root 4.0K Jul 11 2014 multi-user.target.wants drwxr-xr-x. 2 root root 29 May 7 2014 nfs.target.wants drwxr-xr-x. 2 root root 25 Jul 11 2014 printer.target.wants drwxr-xr-x. 2 root root 4.0K Jul 11 2014 sockets.target.wants drwxr-xr-x. 2 root root 35 Jul 11 2014 spice-vdagentd.target.wants drwxr-xr-x. 2 root root 4.0K Jul 11 2014 sysinit.target.wants drwxr-xr-x. 2 root root 83 Jul 11 2014 system-update.target.wants lrwxrwxrwx. 1 root root 9 May 7 2014 tmp.mount -> /dev/null [root@server0 ~]# systemctl list-units --type=target UNIT LOAD ACTIVE SUB DESCRIPTION basic.target loaded active active Basic System cryptsetup.target loaded active active Encrypted Volumes getty.target loaded active active Login Prompts local-fs-pre.target loaded active active Local File Systems (Pre) local-fs.target loaded active active Local File Systems multi-user.target loaded active active Multi-User System network.target loaded active active Network nfs.target loaded active active Network File System Server paths.target loaded active active Paths remote-fs.target loaded active active Remote File Systems slices.target loaded active active Slices sockets.target loaded active active Sockets swap.target loaded active active Swap sysinit.target loaded active active System Initialization timers.target loaded active active Timers LOAD = Reflects whether the unit definition was properly loaded. ACTIVE = The high-level unit activation state, i.e. generalization of SUB. SUB = The low-level unit activation state, values depend on unit type. 15 loaded units listed. Pass --all to see loaded but inactive units, too. To show all installed unit files use 'systemctl list-unit-files'.

[root@server0 ~]# systemctl set-default multi-user.target
rm '/etc/systemd/system/default.target'
ln -s '/usr/lib/systemd/system/multi-user.target' '/etc/systemd/system/default.target'

[root@server0 ~]# systemctl  get-default
multi-user.target

[root@server0 ~]# ls -lh /etc/systemd/system
total 12K
drwxr-xr-x. 2 root root   54 Jul 11  2014 basic.target.wants
drwxr-xr-x. 2 root root   30 Jul 11  2014 bluetooth.target.wants
lrwxrwxrwx. 1 root root   41 Jul 11  2014 dbus-org.bluez.service -> /usr/lib/systemd/system/bluetooth.service
lrwxrwxrwx. 1 root root   41 Jul 11  2014 dbus-org.fedoraproject.FirewallD1.service -> /usr/lib/systemd/system/firewalld.service
lrwxrwxrwx. 1 root root   44 May  7  2014 dbus-org.freedesktop.Avahi.service -> /usr/lib/systemd/system/avahi-daemon.service
lrwxrwxrwx. 1 root root   44 Jul 11  2014 dbus-org.freedesktop.ModemManager1.service -> /usr/lib/systemd/system/ModemManager.service
lrwxrwxrwx. 1 root root   46 May  7  2014 dbus-org.freedesktop.NetworkManager.service -> /usr/lib/systemd/system/NetworkManager.service
lrwxrwxrwx. 1 root root   57 May  7  2014 dbus-org.freedesktop.nm-dispatcher.service -> /usr/lib/systemd/system/NetworkManager-dispatcher.service
lrwxrwxrwx. 1 root root   41 Feb 25 06:29 default.target -> /usr/lib/systemd/system/multi-user.target
drwxr-xr-x. 2 root root   85 May  7  2014 default.target.wants
lrwxrwxrwx. 1 root root   35 Jul 11  2014 display-manager.service -> /usr/lib/systemd/system/gdm.service
drwxr-xr-x. 2 root root   31 May  7  2014 getty.target.wants
drwxr-xr-x. 2 root root   63 Jul 11  2014 graphical.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 multi-user.target.wants
drwxr-xr-x. 2 root root   29 May  7  2014 nfs.target.wants
drwxr-xr-x. 2 root root   25 Jul 11  2014 printer.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 sockets.target.wants
drwxr-xr-x. 2 root root   35 Jul 11  2014 spice-vdagentd.target.wants
drwxr-xr-x. 2 root root 4.0K Jul 11  2014 sysinit.target.wants
drwxr-xr-x. 2 root root   83 Jul 11  2014 system-update.target.wants
lrwxrwxrwx. 1 root root    9 May  7  2014 tmp.mount -> /dev/null

To be reviewd: 
==========
1. 'info grub2', 'man sulogin', 'man dracut.bootup' -> page 69 
2. 'man bootup' -> important.