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Which Style Init Scripts Do You Prefer?
An anonymous reader asks: "I started using Linux years ago, with a Red Hat distribution. When Red Hat's custom configurations started getting in my way, I jumped ship to Slackware. I have never looked back except that I cannot stand the BSD style init scripts. I like having a full compliment of run-levels and control on the fly over which scripts will be running, and which ones will not. That is hard to achieve, when you put multiple configurations in the same file. I also liked having the scripts around to start, stop, and restart services. While I was rewriting my own startup scripts [based on Debian's scripts], I discovered that there is a third style, based on dependencies. AFAIK this is the style adopted by Gentoo. I don't want to start a distro war; but, I am curious about what kind of init scripts Slashdot readers prefer, and what they think are the benefits of each."
You want ssh? /etc/rc.d/sshd start /etc/rc.d/rc.httpd start /etc/rc.d/rc.samba start
Apache?
Samba?
Same goes for nfsd, inetd, gpm, cups, bind, acpid, etc...
rc.6 for restart, rc.0 is statically linked to it to make sure they're always the same.
rc.S is called on runlevel 1 by default, as rc.M is called for 3.
On top of that, if you like your System 5 scripts, call rc.sysvinit.
Where exactly is the problem?
The notion of a run-level is a flaw that is fatal, and will lock you in. However, the BSD's never did lock themselves into this notion, and in fact doesn't support init levels except for compatibility. NetBSD doesn't support init 6 for instance, but freebsd does. I think OpenBSD, and Slackware are the only distro's left that use the old BSD way, as NetBSD and FreeBSD now use rcNG (next generation) in their startup. The think is that system startup is linier in nature (aka in line, and in order). The sysV style startup is based on the shell's lexical ordering, which is nice, but is way too simple. You cannot have complex dependancies like scriptA depends on scriptFOO, and scriptFOO might depend on scriptB. Lexical ordering is easy, but too simple. For example the timed might depend on the network to be started before it can contact the stratum servers. So the new BSD startup scripts has a notion of ordering that isn't dependant on lexical alphabet soup. Your script PROVIDES a service, and might REQUIRE another service before it starts, and might need to run BEFORE another service. These keywords can be placed in commenst of yoru startup scripts to control the startup ordering of the services via the program called rcorder, which parses all the startup scripts, and then executes them in order. This the best way to startup because it doesn't depend on a flawed notion of run-levels which plauge the unix history. the only problem is that they do not provide a way to starup sevices in tandem, or to execute an forget orphan services which neither REQUIRE another service to startup, or need to be run before anything else. It would be possible to speed up startup execution if you could have job-control in the startup scripts. Luck for us the shell can do this, but nobody seems to use it. The problem with having complex dependancies is that you remove the simplicity of lexical orderign which seems so intuative. Now you have to edit the scripts to achive the ordering you want, which is cumbersom, and only for a few seconds increase in overall startup speed. And to think that all this is as simply as /sbin/init executing one user land process (a shell script). Certainly when you think of it this way it is simple, but nobody wants to write startup scripts, which is basicly redesigning the wheel.
It isn't a lie if you belive it.
The company I work for end up with a motley crew of turbolinux machines that had daemontools put on them, I did not like it, but some people swear by being able to do a svc -u /service/apache instead of a /etc/init.d/apache start, I guess it comes down to what you are comfortable with, but I've gotten used to /etc/rc.X/S* start|stop|restart from solaris, just pick one and stay with it.
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