Create Custom Unit File (to run a Custom Daemon) in systemd in RHEL7

In a previous post we configured Swatch Log Monitoring Tool. In this post we will configure swatch as a custom daemon in 'systemd' by creating a custom unit file in 'systemd' and loading it into 'systemd'.


Perform the following steps:

1) Create a unit file in /etc/systemd/system/ directory.
[root@meru ~]# touch /etc/systemd/system/swatch.service

[root@meru ~]# chmod 664 /etc/systemd/system/swatch.service


2) Edit the Unit File.
[root@meru ~]# vi /etc/systemd/system/swatch.service

[Unit]
Description=Swatch Log Monitoring Daemon
After=syslog.target network.target auditd.service sshd.service

[Service]
ExecStart=/bin/swatch --config-file=/etc/swatch/secure.conf --tail-file=/var/log/secure --pid-file=/var/run/swatch.pid --daemon
ExecStop=kill -s KILL $(cat /var/run/swatch.pid)
Type=forking
PIDFile=/var/run/swatch.pid

[Install]
WantedBy=multi-user.target

Where:

• Description is an informative description that is displayed in journal log files and in the output of the systemctl status command. 
   
• After setting ensures that the service is started only after the given space-separated list of services or targets are running.
   
• ExecStart stands for the path to the actual service executable. 
   
• Type=forking is used for daemons that make the fork system call. The main process of the service is created with the PID specified in PIDFile. 
   
• WantedBy states the target or targets that the service should be started under. 

3) Notify systemd about the new swatch.service file.
[root@meru system]# systemctl daemon-reload

4) Start Swatch service
[root@meru system]# systemctl start swatch.service

You can now use all systemctl commands for swatch.service.