How can this init script start without its dependency?

Question

I'm working on some lsb init scripts. Here's the init info from one of them:

### BEGIN INIT INFO
# Provides:     myscript
# Required-Start:   networking myotherscript
# Required-Stop:    networking myotherscript
# Default-Start:    2 3 4 5
# Default-Stop:     0 1 6
# Short-Description:    Starts my daemon
### END INIT INFO

And the init info from myotherscript

### BEGIN INIT INFO
# Provides:     myotherscript
# Required-Start:   networking
# Required-Stop:    networking
# Default-Start:    2 3 4 5
# Default-Stop:     0 1 6
# Short-Description:    Starts my other daemon
### END INIT INFO

If I understand correctly, running service myscript start should not work unless myotherscript is running. However, executing service myscript start does indeed work.

Why don't I at least get an error about the unmet dependency?

Answer 1

The service command doesn't do much more than run the init script with the provided argument. In particular, it doesn't take care of dependencies.

On Fedora/RHEL/CentOS and on Debian/Ubuntu/Mint (and probably others), the dependencies recorded in comments are only taken into account by the service script management utility chkconfig. They are not taken into account if you invoke a script directly, the idea being that if you're doing that, you're intervening directly and want fine control over what services you're manipulating (for example, you may be running a locally-installed version of a dependency, or you may be running it in a different guest in a virtualized environment). This is compliant with the LSB which only specifies the interface between applications and distributions, not between distributions and administrators.

A lack of built-in support for dependencies is one of the defects of SysVinit, which is slowly being phased out in favor of Systemd.