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System boot

Run a command on startup in Linux

Crontab

Put the command in your crontab file. Run command sudo crontab -e to open your crontab file. At the first available line, type "@reboot xxxx", where "xxxx" is the command you wish to run. Save the file and exit.

Add systemd service

Create file /usr/lib/systemd/system/restore-iptables-rules.service or at another location /etc/systemd/system/restore-iptables-rules.service:

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/bash /home/nik/scripts/restore-iptables-rules.service

[Install]
WantedBy=multi-user.target

File /home/nik/scripts/restore-iptables-rules.service:

sudo /usr/sbin/iptables-restore < /etc/sysconfig/iptables

Enable this service:

systemctl enable restore-iptables-rules.service

Show logs of the service:

journalctl -u restore-iptables-rules.service -b -f
  • -u (--unit) - name of the unit
  • -b (--boot) - show info only about the current boot, no older messages
  • -f - follow logs

Add / Remove service to startup

If you want to edit services started at system startup use following commands.

Ubuntu

Method 1

sudo systemctl status apache2
sudo systemctl enable apache2
sudo systemctl disable apache2

Method 2

sudo update-rc.d apache2 defaults

sudo update-rc.d apache2 remove

This command will create / remove the symlink /etc/rc0.d/K01apache2 to /etc/init.d/apache2.

Centos 7

Method 1

Start Docker automatically on boot:

sudo systemctl enable docker

# Created symlink /etc/systemd/system/multi-user.target.wants/docker.service → /usr/lib/systemd/system/docker.service.

Disable Docker start on boot:

sudo systemctl disable docker
# Removed /etc/systemd/system/multi-user.target.wants/docker.service.

Method 2

If you want to automatically start php-fpm on a system boot:

chkconfig php-fpm on

# Note: Forwarding request to 'systemctl enable php-fpm.service'.
# Created symlink from /etc/systemd/system/multi-user.target.wants/php-fpm.service 
# to /usr/lib/systemd/system/php-fpm.service.

Method 3

Create file /usr/lib/systemd/system/kafka-update-crm-status.service:

[Unit]
Description=Kafka Update CRM status
After=network.target

[Service]
User=nginx
Group=sales
Restart=always
RestartSec=100
ExecStart=/usr/bin/php /var/www/mysite/current/protected/yiic.php kafkaMessagesListener

[Install]
WantedBy=multi-user.target

Note 1: Don't add & after the ExecStart command. It's wrong:

ExecStart=/usr/bin/php /var/www/mysite/current/protected/yiic.php kafkaMessagesListener &

Note 2: Ensure that you defined correct values for User, Group.

Commands:

# Reload config. It's safe to run on production
systemctl daemon-reload

service kafka-update-crm-status start
service kafka-update-crm-status status

# Add script to autoload
systemctl enable kafka-update-crm-status

# Read logs
journalctl -u kafka-update-crm-status -f

Run N processes with 1 systemd service

The @ in the service filename lets you start N processes - file /usr/lib/systemd/system/kafka-client-data-consumer-@.service:

[Unit]
Description=Kafka Consumer for client update, instance %i
After=network.target

[Service]
Type=simple
User=root
Restart=always
RestartSec=60
ExecStart=/usr/bin/php /var/www/mysite/current/protected/yiic.php clientConsumer

[Install]
WantedBy=multi-user.target

Commands:

# 1 worker
systemctl start kafka-client-data-consumer-\@1
systemctl status kafka-client-data-consumer-\@1

# 3 workers
systemctl start kafka-client-data-consumer-\@{1..3}
systemctl status kafka-client-data-consumer-\@{1..3}
systemctl stop kafka-client-data-consumer-\@{1..3}

Then be sure to reload:

sudo systemctl daemon-reload