How to Manage ‘Systemd’ Services and Units Using ‘Systemctl’ in Linux

Systemctl is a systemd utility which is responsible for Controlling the systemd system and service manager.

Systemd is a collection of system management daemons, utilities and libraries which serves as a replacement of System V init daemon. Systemd functions as central management and configuration platform for UNIX like system.

In the Linux Ecosystem Systemd has been implemented on most of the standard Linux Distribution with a few exception. Systemd is the parent Process of all other daemons oftenly but not always.

Manage Linux Services Using Systemctl

This article aims at throwing light on “How to control System and Services” on a system running systemd.

Starting with Systemtd and Systemctl Basics

1. First check if systemd is installed on your system or not and what is the version of currently installed Systemd?

# systemd --version
systemd 215
+PAM +AUDIT +SELINUX +IMA +SYSVINIT +LIBCRYPTSETUP +GCRYPT +ACL +XZ -SECCOMP -APPARMOR

It’s clear from the above example, that we have systemd 215 version Installed.

2. Check where the binaries and libraries of systemd and systemctl are installed.

# whereis systemd 
systemd: /usr/lib/systemd /etc/systemd /usr/share/systemd /usr/share/man/man1/systemd.1.gz
# whereis systemctl
systemctl: /usr/bin/systemctl /usr/share/man/man1/systemctl.1.gz

3. Check whether systemd is running or not.

# ps -eaf | grep [s]ystemd
root         1     0  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd --switched-root --system --deserialize 23
root       444     1  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd-journald
root       469     1  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd-udevd
root       555     1  0 16:27 ?        00:00:00 /usr/lib/systemd/systemd-logind
dbus       556     1  0 16:27 ?        00:00:00 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation

Notice: systemd is running as parent daemon (PID=1). In the above command ps with (-e) select all Processes, (-a) select all processes except session leaders and (-f) for full format listing (i.e. -eaf).

Also note the square brackets in the above example and rest of the examples to follow. Square Bracket expression is part of grep’s character class pattern matching.

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