SystemD

Konfiguration

/etc/systemd/journald.conf

Storage=persistent
SystemMaxFileSize=50M

• systemctl restart systemd-journald.service

Kommandos

systemctl

systemctl start nginx.service | stop | status | restart | reload
systemctl enable nginx.service | disable

systemctl list-units # laufende Services
systemctl list-unit-files # verfügbare Services
systemctl --failed # missglückte Starts

systemctl mask nginx.service # Als nicht startbar markieren
systemctl unmask nginx.service # mask aufheben

systemctl list-units --type=target
systemctl isolate graphical.target | rescue.target | multi-user.target 
systemctl set-default multi-user.target

systemd-analyze
systemd-analyze blame # Startzeiten der Services

journalctl

journalctl --since yesterday | --since "2016-03-16 02:00:00" | --since 09:00 --until "1 hour ago"
journalctl --list-boots
journalctl -b -1 # since last boot (relative pointer -1)
journalctl -u nginx.service -u php-fpm.service # by units
journalctl -k # kernel messages
journalctl --no-full # truncated info
journalctl -a # all info
journalctl -n 20 # only the last 20 lines
journalctl -f # like tail -f

journalctl --disk-usage # wie viel braucht das journal
journalctl --vacuum-size=1G # Platz auf 1 GByte reduzieren

Beispiel Service Definitionsdatei

• /lib/systemd/system/redis.service

[Unit]
Description=Redis persistent key-value database
After=network.target

[Service]
ExecStart=/usr/local/bin/redis-server
ExecStop=/usr/local/bin/redis-shutdown
WorkingDirectory=/var/lib/redis
User=redis
Group=redis

[Install]
WantedBy=multi-user.target

Konfiguration

• Einzelkonfigurationen in /etc/systemd.d

cat > /etc/sysctl.d/98-no_overcommit.conf <<EOS
# Select memory overcommitment operation mode.
#
# Mode 2 means that no more than
#
# SwapTotal + (MemTotal * vm.overcommit_ratio / 100)
#
# virtual memory can be allocated (Committed_AS) by processes. The resulting
# limit will be displayed as CommitLimit. (All CamelCased values mentioned
# here can be found in "/proc/meminfo".)
#
# Mode 1 means infinite overcommit - every allocation is allowed, no matter
# how much memory is actually available.
#
# Mode 0 is similar but considers the available RAM when granting large
# allocations - as long as only small allocations are made, they are also
# always allowed.
vm.overcommit_memory = 2

# The conservative default for this is 50 %, meaning that at least half of the
# RAM is left free for buffers and cache (after all swap has been filled up
# already).
#
# Setting it to 98 % in the hope that 2 % free RAM will still be enough for all basic
# system operation besides the page cache (for block buffers and kernel).
vm.overcommit_ratio = 98
EOS