🐧 Как выполнить команду перед запуском службы

Выполните команду перед запуском службы.

Проверьте состояние службы, которая будет использоваться в качестве примера.

$ systemctl status gdm

● gdm.service - GNOME Display Manager
     Loaded: loaded (/usr/lib/systemd/system/gdm.service; static)
     Active: active (running) since Mon 2024-11-18 23:27:08 CET; 8min ago
   Main PID: 1799 (gdm3)
      Tasks: 4 (limit: 9324)
     Memory: 6.4M (peak: 8.7M)
        CPU: 82ms
     CGroup: /system.slice/gdm.service
             └─1799 /usr/sbin/gdm3

Nov 18 23:27:08 desktop systemd[1]: Starting gdm.service - GNOME Display Manager...
Nov 18 23:27:08 desktop systemd[1]: Started gdm.service - GNOME Display Manager.
Nov 18 23:27:08 desktop gdm-launch-environment][1806]: pam_unix(gdm-launch-environment:session): session open>
Nov 18 23:27:15 desktop gdm-password][2355]: gkr-pam: unable to locate daemon control file
Nov 18 23:27:15 desktop gdm-password][2355]: gkr-pam: stashed password to try later in open session
Nov 18 23:27:15 desktop gdm-password][2355]: pam_unix(gdm-password:session): session opened for user milosz(u>
Nov 18 23:27:15 desktop gdm-password][2355]: gkr-pam: unlocked login keyring
Nov 18 23:27:17 desktop gdm3[1799]: Gdm: Child process -1842 was already dead.

Проверьте файл конфигурации, который будет изменен перед запуском службы.

$ cat /etc/gdm3/custom.conf 

# GDM configuration storage
#
# See /usr/share/gdm/gdm.schemas for a list of available options.

[daemon]
# Uncomment the line below to force the login screen to use Xorg
#WaylandEnable=false

# Enabling automatic login
#  AutomaticLoginEnable = true
#  AutomaticLogin = user1

# Enabling timed login
#  TimedLoginEnable = true
#  TimedLogin = user1
#  TimedLoginDelay = 10

[security]

[xdmcp]

[chooser]

[debug]
# Uncomment the line below to turn on debugging
# More verbose logs
# Additionally lets the X server dump core if it crashes
#Enable=true

Создайте каталог переопределения служб.

$ sudo mkdir /etc/systemd/system/gdm.service.d

Создайте переопределение службы, которое изменит файл конфигурации.

$ echo -e "[Service]\nExecStartPre=/bin/sed -i 's/AutomaticLoginEnable=.*/AutomaticLoginEnable=false/g' /etc/gdm3/custom.conf\nExecStartPre=/bin/sed -i '/^AutomaticLogin=/d' /etc/gdm3/custom.conf" | \
  sudo tee /etc/systemd/system/gdm.service.d/disable_automatic_login.conf

[Service]
ExecStartPre=/bin/sed -i 's/AutomaticLoginEnable=.*/AutomaticLoginEnable=false/g' /etc/gdm3/custom.conf
ExecStartPre=/bin/sed -i '/^AutomaticLogin=/d' /etc/gdm3/custom.conf

Перезагрузите конфигурацию systemd.

$ sudo systemctl daemon-reload 

Проверьте состояние службы.

$ systemctl status gdm

● gdm.service - GNOME Display Manager
     Loaded: loaded (/usr/lib/systemd/system/gdm.service; static)
    Drop-In: /etc/systemd/system/gdm.service.d
             └─disable_automatic_login.conf
     Active: active (running) since Mon 2024-11-18 23:27:08 CET; 14min ago
   Main PID: 1799 (gdm3)
      Tasks: 4 (limit: 9324)
     Memory: 6.3M (peak: 8.7M)
        CPU: 82ms
     CGroup: /system.slice/gdm.service
             └─1799 /usr/sbin/gdm3

Nov 18 23:27:08 desktop systemd[1]: Starting gdm.service - GNOME Display Manager...
Nov 18 23:27:08 desktop systemd[1]: Started gdm.service - GNOME Display Manager.
Nov 18 23:27:08 desktop gdm-launch-environment][1806]: pam_unix(gdm-launch-environment:session): session open>
Nov 18 23:27:15 desktop gdm-password][2355]: gkr-pam: unable to locate daemon control file
Nov 18 23:27:15 desktop gdm-password][2355]: gkr-pam: stashed password to try later in open session
Nov 18 23:27:15 desktop gdm-password][2355]: pam_unix(gdm-password:session): session opened for user milosz(u>
Nov 18 23:27:15 desktop gdm-password][2355]: gkr-pam: unlocked login keyring
Nov 18 23:27:17 desktop gdm3[1799]: Gdm: Child process -1842 was already dead.

Изменение файла конфигурации.

Проверьте файл конфигурации.

$ cat /etc/gdm3/custom.conf 

# GDM configuration storage
#
# See /usr/share/gdm/gdm.schemas for a list of available options.

[daemon]
AutomaticLoginEnable=True
AutomaticLogin=milosz
# Uncomment the line below to force the login screen to use Xorg
#WaylandEnable=false

# Enabling automatic login
#  AutomaticLoginEnable = true
#  AutomaticLogin = user1

# Enabling timed login
#  TimedLoginEnable = true
#  TimedLogin = user1
#  TimedLoginDelay = 10

[security]

[xdmcp]

[chooser]

[debug]
# Uncomment the line below to turn on debugging
# More verbose logs
# Additionally lets the X server dump core if it crashes
#Enable=true

Перезапустите операционную систему или службу, которая используется в этом примере.

$ sudo systemctl restart gdm

Просмотрите файл конфигурации.

$ cat /etc/gdm3/custom.conf 

# GDM configuration storage
#
# See /usr/share/gdm/gdm.schemas for a list of available options.

[daemon]
AutomaticLoginEnable=false
# Uncomment the line below to force the login screen to use Xorg
#WaylandEnable=false

# Enabling automatic login
#  AutomaticLoginEnable = true
#  AutomaticLogin = user1

# Enabling timed login
#  TimedLoginEnable = true
#  TimedLogin = user1
#  TimedLoginDelay = 10

[security]

[xdmcp]

[chooser]

[debug]
# Uncomment the line below to turn on debugging
# More verbose logs
# Additionally lets the X server dump core if it crashes
#Enable=true

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