If you use Linux you most likely have heard of the init.d directory. But what exactly does this directory do? It ultimately does one thing but it does that one thing for your entire system, so init.d is very important. The init.d directory contains a number of start/stop scripts for various services on your system. Everything from acpid to x11-common is controlled from this directory. Of course it’s not exactly that simple.
If you look at the /etc directory you will find directories that are in the form rc#.d (Where # is a number reflects a specific initialization level – from 0 to 6). Within each of these directories is a number of other scripts that control processes. These scripts will either begin with a “K” or an “S”. All “K” scripts are run before “S” scripts. And depending upon where the scripts are located will determine when the scripts initiate. Between the directories the system services work together like a well-oiled machine. But there are times when you need to start or stop a process cleanly and without using the kill or killall commands. That is where the /etc/init.d directory comes in handy.
Now if you are using a distribution like Fedora you might find this directory in /etc/rc.d/init.d. Regardless of location, it serves the same purpose.
In order to control any of the scripts in init.d manually you have to have root (or sudo) access. Each script will be run as a command and the structure of the command will look like:
/etc/init.d/command OPTION
Where command is the actual command to run and OPTION can be one of the following:
- start
- stop
- reload
- restart
- force-reload
Most often you will use either start, stop, or restart. So if you want to stop your network you can issue the command:
/etc/init.d/networking stop
Or if you make a change to your network and need to restart it, you could do so with the following command:
/etc/init.d/networking restart
Some of the more common init scripts in this directory are:
- networking
- samba
- apache2
- ftpd
- sshd
- dovecot
- mysql
Of course there may be more often-used scripts in your directory – it depends upon what you have installed. The above list was taken from a Ubuntu Server 8.10 installation so a standard desktop installation would have a few less networking-type scripts.
But what about /etc/rc.local
There is a third option that I used to use quite a bit. This option is the /etc/rc.local script. This file runs after all other init level scripts have run, so it’s safe to put various commands that you want to have issued upon startup. Many times I will place mounting instructions for things like nfs in this script. This is also a good place to place “troubleshooting” scripts in. For instance, once I had a machine that, for some reason, samba seemed to not want to start. Even afer checking to make sure the Samba daemon was setup to initialize at boot up. So instead of spending all of my time up front with this I simply placed the line:
/etc/init.d/samba start
in the /etc/rc.local script and Samba worked like a charm. Eventually I would come back and trouble shoot this issue.
Final Thoughts
Linux is flexible. Linux is so flexible there is almost, inevitably, numerous ways to solve a single problem. Starting a system service is one such issue. With the help of the /etc/init.d system (as well as /etc/rc.local) you can pretty much rest assured your service will start.
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I ran into this command on Friday on my RHEL server which I thought was helpful:
chkconfig
‘chkconfig’ allows the checking the startup level of services and gives the ability to set the service. Running ‘chkconfig’ will setup the scripts in the needed “rcX.d” directory.
other command of use:
/sbin/service “stop|start|restart|etc”
this command is the equiv of typing “/etc/init.d/ ….”
thank you.
well explained.
Great explanation, am new to linux and this explained the init.d directory quite easily….Altough i know the to be involved in the run level and service initialisation in the booting process.please post an article on that too..
May I know how we can create a new file in the init.d folder. I’ve used ‘touch’ command but it is saying ‘permission denied’ even though im the superuser (root). I’m actually installing subversion on my linux machine and I need to create and a new file in the init.d folder to configure the subversion server.
could you please help me with this.
Thank you
to Abhilash:
Even though you are logged in as root, try putting sudo before the touch command.
sudo touch /etc/init.d/
sorry… sudo touch /etc/init.d/FILE NAME
Hello i want to know how i can make crontab for my ircd ?im using bahamut,when shell is geeetong rebooting ircd is going down and it wont work untill i got to shell i up it myself,i want it to be up automatically,as my srvices when i kill them,or restart.Please help me with it.thanks./
could you add further explanations about the options.
i.e Whats the difference between ‘reload’ and ‘restart’?
@rs reload will usually try reload the service’s configuration files without stopping the service (if possible). Often a restart is basically equivalent of doing a ‘service x stop’ then immediately doing a ‘service x start’, though how this works depends wholly on the script involved.
I kind of messed up with this directory. I was trying to remove a startup script from the /etc/init.d using rm and by mistake i removed the entire /etc/init.d . later i googled to find that /etc/init.d is a symlink to /etc/rc.d/init.d ; so i created to symlink /etc/init.d . what i did is that rite?
I think your explanation regarding script naming and execution is incorrect.
Script whose name is starting with an S ( start ) will be executed at that particular run level and scripts whose name is starting with a K ( kill ) will be killed at that particular run level and will not run at all.
The number after an S or K determines an order in which these scripts are executed.
Hi,
How do you restart all services instead of doing it one by one?
EG: /etc/init.d/httpd restart
How do I restart everything in /etc/init.d ?
@jamal
Init 2 on ubuntu
Init 5 on red hat
You have:
“/etc/initi.d/command OPTION”
This needs to be changed to:
“/etc/init.d/command OPTION”
ie “initi.d” needs to changed to “init.d”
Wayne Sallee
Wayne@WayneSallee.com
Thanks Wayne, have corrected it.
what will happen when we type “/etc/init.d”
dear all,
currently i had install to setup connecting between sun solaris and titan ups server..
i need to know about etc/init.d
Thanks — this was a very clear and informative posting. It answered every question I had about init.d