On Debian-based systems, init.d scripts in /etc/init.d/ control service lifecycles through standardized commands:

sudo /etc/init.d/scriptname start|stop|restart|status

To run a service manually while preventing automatic startup:

# Example for Apache2
sudo update-rc.d -f apache2 remove
sudo /etc/init.d/apache2 start

For persistent changes across reboots:

Method 1: Using update-rc.d

# Disable
sudo update-rc.d servicename disable

# Re-enable later if needed
sudo update-rc.d servicename enable

Method 2: Systemd Compatibility Layer

# For systems with systemd but using sysvinit scripts
sudo systemctl disable servicename.service
sudo systemctl mask servicename.service  # Stronger prevention

Confirm your changes took effect:

# Check runlevel links
ls -l /etc/rc*.d/ | grep servicename

# Verify boot behavior
sudo service servicename status

Complete workflow for MySQL management:

# Remove from startup
sudo update-rc.d mysql remove

# Manual control
sudo /etc/init.d/mysql start
sudo /etc/init.d/mysql stop

# Temporary auto-start (for maintenance)
sudo update-rc.d mysql defaults

In Debian-based systems, traditional SysV init scripts located in /etc/init.d/ can be controlled through various mechanisms. The challenge arises when you want to:

• Prevent automatic execution during system boot
• Maintain the ability to manually start/stop the service

The most effective method involves modifying the service's runlevel configuration:

# First check current runlevel configuration
ls -l /etc/rc*.d/*servicename*

# To disable automatic startup for all runlevels
update-rc.d -f servicename remove

# Alternative method (Debian/Ubuntu)
systemctl disable servicename

After disabling auto-start, you can still manage the service manually:

# Start service manually
/etc/init.d/servicename start
# or
service servicename start

# Stop service manually
/etc/init.d/servicename stop
# or
service servicename stop

# Check status
/etc/init.d/servicename status

Let's demonstrate with Apache web server:

# Disable automatic startup
sudo update-rc.d -f apache2 remove

# Verify it won't start at boot
ls -l /etc/rc*.d/*apache2*  # Should show no links

# Manual control remains available
sudo service apache2 start
sudo service apache2 stop

For systems with chkconfig installed:

# Disable auto-start
sudo chkconfig servicename off

# Manual control
sudo service servicename start

• Some services may have dependencies that need manual handling
• Changes persist across reboots
• Always verify service status after modifications
• For systemd systems, consider using systemctl mask instead