Configure Linux Services for Automatic Startup with systemd, chkconfig, and crontab

1. System Services

If a component is installed as a system service, its unit file (e.g., xxx.service) resides in /usr/lib/systemd/system. Two common ways to enable boot start are described.

systemctl method

systemctl enable xxx      # enable boot start
systemctl disable xxx     # cancel boot start

Check status with: systemctl status chronyd.service List enabled or disabled services:

systemctl list-unit-files --state=enabled
systemctl list-unit-files --state=disabled

Use --state together with list-units for more detailed queries.

chkconfig method (more complex)

chkconfig --add xxx && chkconfig --level 3 xxx on/off

View SysV services (does not include native systemd units): chkconfig --list network To list systemd services, use systemctl list-unit-files or systemctl list-dependencies [target].

Special note: The systemctl enable command creates a symlink under /etc/systemd/system/ (or /etc/systemd/user/) pointing to the original unit file, e.g.:

# systemctl enable mysqld
Created symlink from /etc/systemd/system/multi-user.target.wants/mysqld.service to /usr/lib/systemd/system/mysqld.service.

To disable boot start, either run systemctl disable xxx or remove the corresponding symlink.

2. Generic Solutions

Regardless of whether a component is already a system service, you can use boot scripts. All scripts must be executable ( chmod +x).

Method 1: Append the start command to /etc/rc.local (or its symlink /etc/rc.d/rc.local).

Method 2: Place a .sh script in /etc/profile.d.

Method 3: Write a .sh script and add its execution line to /etc/rc.local or /etc/rc.d/rc.local.

3. crontab Solution

crontab supports special keywords prefixed with @ to replace the five time fields. Common forms:

@reboot   : Run once after reboot (executes earlier than rc.local by ~1‑2 seconds)
@yearly   : Run once a year ("0 0 1 1 *")
@annually : Same as @yearly
@monthly  : Run once a month ("0 0 1 * *")
@weekly   : Run once a week ("0 0 * * 0")
@daily    : Run once a day ("0 0 * * *")
@hourly   : Run once an hour ("0 * * * *")

Example to start a daemon after reboot:

# crontab -e
@reboot /usr/local/daemonProcess/somescript.sh

If a regular interval task is also needed, decide whether @reboot and the periodic schedule overlap; avoid duplicate starts when the service cannot handle them.

4. Production‑Environment Recommendation

In production, adopt a single boot‑start method for all components to simplify operations. Mixing methods (systemd, rc scripts, crontab) can increase maintenance effort and error risk, especially when services lack native systemd units.

Appendix: Sample Startup Script

# Make rc.local executable
chmod +x /etc/rc.d/rc.local

# Example startup script
/usr/local/AutoStartOnBoot.sh
chmod +x /usr/local/AutoStartOnBoot.sh
source /etc/profile   # load environment before rc.local runs

# Start services
/usr/local/redis/redis-5.0.13/bin/redis-server /usr/local/redis/redis-5.0.13/conf/redis.conf
rm -f /data/zookeeper/data/zookeeper_server.pid
/usr/local/apache-zookeeper-3.6.3-bin/bin/zkServer.sh start
JMX_PORT=9999 /usr/local/kafka_2.13-2.7.1/bin/kafka-server-start.sh -daemon /usr/local/kafka_2.13-2.7.1/config/server.properties
rm -f /usr/local/kafka-manager-2.0.0.2/RUNNING_PID
nohup /usr/local/kafka-manager-2.0.0.2/bin/kafka-manager -Dconfig.file=/usr/local/kafka-manager-2.0.0.2/conf/application.conf -Dhttp.port=9002 >/dev/null 2>&1 &
service mysqld start