In RHEL 5 and 6, we were using automatic startup feature of RHEL through /etc/rc.d/init.d to run any script at system boot. Starting with RHEL 7 init is replaced by systemd and the prior method is now deprecated. There is another way in RHEL 7 to do the same.
Creating the custom script
1. Let us first create a sample custom script to be run at system boot automatically.
# vi /var/tmp/test_script.sh #!/bin/bash echo "This is a sample script to test auto run during boot" > /var/tmp/script.out echo "The time the script run was --> `date`" >> /var/tmp/script.out
2. Check and verify the file permission.
# ls -lrt /usr/local/sbin/myscript.sh
3. Add execute permission(if it’s not already set).
# chmod +x /var/tmp/test_script.sh
Creating new systemd service unit
Create a new service unit file at /etc/systemd/system/sample.service with below content. The name of the service unit is user defined and can be any name of your choice.
# vi /etc/systemd/system/sample.service [Unit] Description=Description for sample script goes here After=network.target [Service] Type=simple ExecStart=/var/tmp/test_script.sh TimeoutStartSec=0 [Install] WantedBy=default.target
Here,
After =: If the script needs any other system facilities (networking, etc), modify the [Unit] section to include appropriate After=, Wants=, or Requires= directives.
Type= : Switch Type=simple for Type=idle in the [Service] section to delay execution of the script until all other jobs are dispatched
WantedBy= : target to run the sample script in
Enable the systemd service unit
1. Reload the systemd process to consider newly created sample. service OR every time when sample.service gets modified.
# systemctl daemon-reload
2. Enable this service to start after reboot automatically.
# systemctl enable sample.service
3. Start the service.
# systemctl start sample.service
4. Reboot the host to verify whether the scripts are starting as expected during system boot.
# systemctl reboot
