CentOS7 Cheat Sheet | ソフトウェア開発のギークフィード


Systemd Cheat Sheet

View Systemd Information

# systemctl list-dependencies

Show a unit’s dependencies

# systemctl list-sockets

List sockets and what activates

# systemctl list-jobs

View Active systemd jobs

# systemctl list-unit-files

See unit files and their states

# systemctl list-units

Show if units are loaded/active

# systemctl get-default

List default target (like run level)

Working with Services

# systemctl stop SERVICE_NAME

Stop a running service

# systemctl start SERVICE_NAME

Start a service

# systemctl restart SERVICE_NAME

Restart a running service

# systemctl reload SERVICE_NAME

Reload all config files in service

# systemctl status SERVICE_NAME

See if service is running/enabled

# systemctl enable SERVICE_NAME

Enable a service to start on boot

# systemctl disable SERVICE_NAME

Disable service — won’t start on boot

# systemctl show SERVICE_NAME

Show properties of a service (or other unit)

# systemctl -H HOST_ADDRESS status SERVICE_NAME

Run any systemctl command remotely

Changing System States

# systemctl reboot

Reboot the system (reboot.target)

# systemctl poweroff

Power off the system (poweroff.target)

# systemctl emergency

Put in emergency mode (emergency.target)

# systemctl default

Back to default target (multi-user.target)

Viewing Log Messages

# journalctl

Show all collected log messages

# journalctl -u network.service

See network service messages

# journalctl -f

Follow messages as they appear

# journalctl -k

Show only kernel messages

Using Unit Files

Besides services, most systemd commands can work with these unit types:
parths, slices, snapshots, sockets, swaps, targets, and times


arp -a
ip neigh
arp -v
ip -s neigh
arp -s 1:2:3:4:5:6
ip neigh add lladdr 1:2:3:4:5:6 dev eth1
arp -i eth1 -d
ip neigh del dev eth1
ifconfig -a
ip addr
ifconfig eth0 down
ip link set eth0 down
ifconfig eth0 up
ip link set eth0 up
ifconfig eth0
ip addr add dev eth0
ifconfig eth0 netmask
ip addr add dev eth0
ifconfig eth0 mtu 9000
ip link set eth0 mtu 9000
ifconfig eth0:0
ip addr add dev eth0
netstat -neopa
ss -neopa
netstat -g
ip maddr
ip route
route add -net netmask dev eth0
ip route add dev eth0
route add default gw
ip route add default via

Firewalld commandline Cheat Sheet

Managing firewalld

# firewall-cmd –state

Check whether the firewalld daemon is active

# firewall-cmd –reload

Reload firewall rules and keep state information.

To list detalls of default and active zones

# firewall-cmd –get-default-zone

Print default zone for connections and interfaces.

# firewall-cmd –get-active-zones

Print currently active zones altogether with interfaces
and sources used in these zones.

# firewall-cmd –list-all -zones

List everything added for or enabled in all zones.

To add/remove interfaces to zones

# firewall-cmd –zone=public –change-interface=eth1

To add interface “eth1” to “public” zone

To list/add/remove services to zones

# firewall-cmd –get-services

Print predefined services as a space separated list.

# firewall-cmd –zone=public –add-service=
samba –add-service=samba-client –permanent

Add “samba and samba-client” service to a specific zone.
You may include, “permanent” flag to make this permanent change.

# firewall-cmd –zone=public –list-service

List services configured in public zone

To list and Add ports to firewall

# firewall-cmd –list-port

List ports added for default zone as a space separated list.

# firewall-cmd –zone=public –add-port=5000/tcp

Add ports in a public zone