Progmar Marcin Załęczny

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Systemd

Displays unit files list of the systemd init process: sudo systemctl list-unit-files

Displays a list of services that could not be run while system startup: sudo systemctl --state=failed

Displays detailed information about specified service: sudo systemctl status mysql.service

Stops specified service: sudo systemctl stop mysql

Starts specified service: sudo systemctl start mysql

Kills all processes that belongs to specified service: sudo systemctl kill mysql

Sends SIGHUP signal to the test process of specified service: sudo systemctl kill -s HUP --kill-who=test mysql

Makes a specified service not to run during system startup: sudo systemctl disable mysql

Makes a specified service to run during system startup: sudo systemctl enable mysql

To run a custom script (here: /usr/local/bin/firewall.sh) during system startup, first we need to create a unit file for the script, for ex.: /lib/systemd/system/firewall.service with the following content:

# iptables firewall service file

[Unit]
Description=Iptables firewall and fwsnort rules
After=network.target
After=syslog.target

[Install]
WantedBy=multi-user.target

[Service]
User=root
Group=root
ExecStart=/usr/local/bin/firewall.sh
Next we enables the service: sudo systemctl enable firewall

Displays load time stats for all services being run at the system startup (both kernel and user space): systemd-analyze

Displays load time stats for all services being run: systemd-analyze blame

Generates a load time stats plot for all services: systemd-analyze plot >plot.svg View created plot with eye of gnome application: eog plot.svg

Displays system journal messages since last system startup: sudo journalctl

Displays system journal error messages since last system startup: sudo journalctl -b -p err

Displays system journal messages since specified period: sudo journalctl --since=yesterday sudo journalctl --since=2016-05-28

Displays system journal messages within specified time period: sudo journalctl --since=2016-05-27 --until=2016-05-29

Displays system journal messages generated by given service (mysql) within specified time period: sudo journalctl -u mysql --since=yesterday --until=now

Displays all systemd services/units which system journal messages can be filtered for: sudo journalctl -F _SYSTEMD_UNIT

Displays all metadata that was registered ever: sudo journalctl -o verbose -n

Filters system journal messages for specified metadata (here: _UID and _EXEC) and its values: sudo journalctl _UID=0 _EXE=/usr/sbin/thermald