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diff --git a/docs/TIPS_AND_TRICKS.md b/docs/TIPS_AND_TRICKS.md new file mode 100644 index 0000000..f181f12 --- /dev/null +++ b/docs/TIPS_AND_TRICKS.md @@ -0,0 +1,185 @@ +--- +title: Tips And Tricks +category: Manuals and Documentation for Users and Administrators +layout: default +SPDX-License-Identifier: LGPL-2.1-or-later +--- + +# Tips & Tricks + +Also check out the [Frequently Asked Questions](http://www.freedesktop.org/wiki/Software/systemd/FrequentlyAskedQuestions)! + +## Listing running services + +```sh +$ systemctl +UNIT LOAD ACTIVE SUB JOB DESCRIPTION +accounts-daemon.service loaded active running Accounts Service +atd.service loaded active running Job spooling tools +avahi-daemon.service loaded active running Avahi mDNS/DNS-SD Stack +bluetooth.service loaded active running Bluetooth Manager +colord-sane.service loaded active running Daemon for monitoring attached scanners and registering them with colord +colord.service loaded active running Manage, Install and Generate Color Profiles +crond.service loaded active running Command Scheduler +cups.service loaded active running CUPS Printing Service +dbus.service loaded active running D-Bus System Message Bus +... +``` + +## Showing runtime status + +```sh +$ systemctl status udisks2.service +udisks2.service - Storage Daemon + Loaded: loaded (/usr/lib/systemd/system/udisks2.service; static) + Active: active (running) since Wed, 27 Jun 2012 20:49:25 +0200; 1 day and 1h ago + Main PID: 615 (udisksd) + CGroup: name=systemd:/system/udisks2.service + └ 615 /usr/lib/udisks2/udisksd --no-debug + +Jun 27 20:49:25 epsilon udisksd[615]: udisks daemon version 1.94.0 starting +Jun 27 20:49:25 epsilon udisksd[615]: Acquired the name org.freedesktop.UDisks2 on the system message bus +``` + +## cgroup tree + +```sh +$ systemd-cgls +└ system +├ 1 /usr/lib/systemd/systemd --system --deserialize 18 +├ ntpd.service +│ └ 8471 /usr/sbin/ntpd -u ntp:ntp -g +├ upower.service +│ └ 798 /usr/libexec/upowerd +├ wpa_supplicant.service +│ └ 751 /usr/sbin/wpa_supplicant -u -f /var/log/wpa_supplicant.log -c /etc/wpa_supplicant/wpa_supplicant.conf -u -f /var/log/wpa_supplicant.log -P /var/run/wpa_supplicant.pid +├ nfs-idmap.service +│ └ 731 /usr/sbin/rpc.idmapd +├ nfs-rquotad.service +│ └ 753 /usr/sbin/rpc.rquotad +├ nfs-mountd.service +│ └ 732 /usr/sbin/rpc.mountd +├ nfs-lock.service +│ └ 704 /sbin/rpc.statd +├ rpcbind.service +│ └ 680 /sbin/rpcbind -w +├ postfix.service +│ ├ 859 /usr/libexec/postfix/master +│ ├ 877 qmgr -l -t fifo -u +│ └ 32271 pickup -l -t fifo -u +├ colord-sane.service +│ └ 647 /usr/libexec/colord-sane +├ udisks2.service +│ └ 615 /usr/lib/udisks2/udisksd --no-debug +├ colord.service +│ └ 607 /usr/libexec/colord +├ prefdm.service +│ ├ 567 /usr/sbin/gdm-binary -nodaemon +│ ├ 602 /usr/libexec/gdm-simple-slave --display-id /org/gnome/DisplayManager/Display1 +│ ├ 612 /usr/bin/Xorg :0 -br -verbose -auth /var/run/gdm/auth-for-gdm-O00GPA/database -seat seat0 -nolisten tcp +│ └ 905 gdm-session-worker [pam/gdm-password] +├ systemd-ask-password-wall.service +│ └ 645 /usr/bin/systemd-tty-ask-password-agent --wall +├ atd.service +│ └ 544 /usr/sbin/atd -f +├ ksmtuned.service +│ ├ 548 /bin/bash /usr/sbin/ksmtuned +│ └ 1092 sleep 60 +├ dbus.service +│ ├ 586 /bin/dbus-daemon --system --address=systemd: --nofork --systemd-activation +│ ├ 601 /usr/libexec/polkit-1/polkitd --no-debug +│ └ 657 /usr/sbin/modem-manager +├ cups.service +│ └ 508 /usr/sbin/cupsd -f +├ avahi-daemon.service +│ ├ 506 avahi-daemon: running [epsilon.local] +│ └ 516 avahi-daemon: chroot helper +├ system-setup-keyboard.service +│ └ 504 /usr/bin/system-setup-keyboard +├ accounts-daemon.service +│ └ 502 /usr/libexec/accounts-daemon +├ systemd-logind.service +│ └ 498 /usr/lib/systemd/systemd-logind +├ crond.service +│ └ 486 /usr/sbin/crond -n +├ NetworkManager.service +│ ├ 484 /usr/sbin/NetworkManager --no-daemon +│ └ 8437 /sbin/dhclient -d -4 -sf /usr/libexec/nm-dhcp-client.action -pf /var/run/dhclient-wlan0.pid -lf /var/lib/dhclient/dhclient-903b6f6aa7a1-46c8-82a9-7f637dfbb3e4-wlan0.lease -cf /var/run/nm-d... +├ libvirtd.service +│ ├ 480 /usr/sbin/libvirtd +│ └ 571 /sbin/dnsmasq --strict-order --bind-interfaces --pid-file=/var/run/libvirt/network/default.pid --conf-file= --except-interface lo --listenaddress 192.168.122.1 --dhcp-range 192.168.122.2,1... +├ bluetooth.service +│ └ 479 /usr/sbin/bluetoothd -n +├ systemd-udev.service +│ └ 287 /usr/lib/systemd/systemd-udevd +└ systemd-journald.service +└ 280 /usr/lib/systemd/systemd-journald +``` + +### ps with cgroups + +```sh +$ alias psc='ps xawf -eo pid,user,cgroup,args' +$ psc + PID USER CGROUP COMMAND +... + 1 root name=systemd:/systemd-1 /bin/systemd systemd.log_target=kmsg systemd.log_level=debug selinux=0 + 415 root name=systemd:/systemd-1/sysinit.service /sbin/udevd -d + 928 root name=systemd:/systemd-1/atd.service /usr/sbin/atd -f + 930 root name=systemd:/systemd-1/ntpd.service /usr/sbin/ntpd -n + 932 root name=systemd:/systemd-1/crond.service /usr/sbin/crond -n + 935 root name=systemd:/systemd-1/auditd.service /sbin/auditd -n + 943 root name=systemd:/systemd-1/auditd.service \_ /sbin/audispd + 964 root name=systemd:/systemd-1/auditd.service \_ /usr/sbin/sedispatch + 937 root name=systemd:/systemd-1/acpid.service /usr/sbin/acpid -f + 941 rpc name=systemd:/systemd-1/rpcbind.service /sbin/rpcbind -f + 944 root name=systemd:/systemd-1/rsyslog.service /sbin/rsyslogd -n -c 4 + 947 root name=systemd:/systemd-1/systemd-logger.service /lib/systemd/systemd-logger + 950 root name=systemd:/systemd-1/cups.service /usr/sbin/cupsd -f + 955 dbus name=systemd:/systemd-1/messagebus.service /bin/dbus-daemon --system --address=systemd: --nofork --systemd-activation + 969 root name=systemd:/systemd-1/getty@.service/tty6 /sbin/mingetty tty6 + 970 root name=systemd:/systemd-1/getty@.service/tty5 /sbin/mingetty tty5 + 971 root name=systemd:/systemd-1/getty@.service/tty1 /sbin/mingetty tty1 + 973 root name=systemd:/systemd-1/getty@.service/tty4 /sbin/mingetty tty4 + 974 root name=systemd:/user/lennart/2 login -- lennart + 1824 lennart name=systemd:/user/lennart/2 \_ -bash + 975 root name=systemd:/systemd-1/getty@.service/tty3 /sbin/mingetty tty3 + 988 root name=systemd:/systemd-1/polkitd.service /usr/libexec/polkit-1/polkitd + 994 rtkit name=systemd:/systemd-1/rtkit-daemon.service /usr/libexec/rtkit-daemon +... +``` + +## Changing the Default Boot Target + +```sh +$ ln -sf /usr/lib/systemd/system/multi-user.target /etc/systemd/system/default.target +``` + +This line makes the multi user target (i.e. full system, but no graphical UI) the default target to boot into. This is kinda equivalent to setting runlevel 3 as the default runlevel on Fedora/sysvinit systems. + +```sh +$ ln -sf /usr/lib/systemd/system/graphical.target /etc/systemd/system/default.target +``` + +This line makes the graphical target (i.e. full system, including graphical UI) the default target to boot into. Kinda equivalent to runlevel 5 on fedora/sysvinit systems. This is how things are shipped by default. + +## What other units does a unit depend on? + +For example, if you want to figure out which services a target like multi-user.target pulls in, use something like this: + +```sh +$ systemctl show -p "Wants" multi-user.target +Wants=rc-local.service avahi-daemon.service rpcbind.service NetworkManager.service acpid.service dbus.service atd.service crond.service auditd.service ntpd.service udisks.service bluetooth.service cups.service wpa_supplicant.service getty.target modem-manager.service portreserve.service abrtd.service yum-updatesd.service upowerd.service test-first.service pcscd.service rsyslog.service haldaemon.service remote-fs.target plymouth-quit.service systemd-update-utmp-runlevel.service sendmail.service lvm2-monitor.service cpuspeed.service udev-post.service mdmonitor.service iscsid.service livesys.service livesys-late.service irqbalance.service iscsi.service netfs.service +``` + +Instead of "Wants" you might also try "WantedBy", "Requires", "RequiredBy", "Conflicts", "ConflictedBy", "Before", "After" for the respective types of dependencies and their inverse. + +## What would get started if I booted into a specific target? + +If you want systemd to calculate the "initial" transaction it would execute on boot, try something like this: + +```sh +$ systemd --test --system --unit=foobar.target +``` + +for a boot target foobar.target. Note that this is mostly a debugging tool that actually does a lot more than just calculate the initial transaction, so don't build scripts based on this. |