Understand systemd¶

Systemd¶

Framework¶

Basic Command¶

syntax¶

list units:

$ systemctl list-units
$ systemctl list-units --all
    $ systemctl list-units --type service --all

start/stop service:

# systemctl start [name.service]
# systemctl stop [name.service]
# systemctl restart [name.service]
# systemctl reload [name.service]
$ systemctl status [name.service]
# systemctl is-active [name.service]

Service List¶

Service: Linux Service

Target: group of units

Automount: filesystem auto-mountpoint

Device: kernel device names, which you can see in sysfs and udev

Mount: filesystem mountpoint

Path: file or directory

Scope: external processes not started by systemd

Slice: a management unit of processes

Snapshot: systemd saved state

Socket: IPC (inter-process communication) socket

Swap: swap file

Timer: systemd timer.

Test¶

    sudo su -
dnf install httpd
systemctl start httpd.service
     -- หรือ --
systemctl start httpd.service
systemctl enable httpd.service

Unit Detail¶

    systemctl cat httpd
systemctl list-dependencies httpd

Dependencies¶

systemctl list-dependencies sshd.service

Checking Unit Properties¶

systemctl show sshd.service

Masking and Unmasking Units¶

    systemctl mask httpd
systemctl start httpd
systemctl unmask httpd
systemctl start httpd