Linux web host - all daemons or server processes that should be
all daemons or server processes that should be running in the new run level. This loop performs the same checks to ignore broken links and files lingering from previous RPM package installations. Also, the rc script will not attempt to start a daemon if its lock files in the /var/lock/subsys directory exist, indicating that the daemon is already running. The next block of code implements the aforementioned daemon startup confirmation process, prompting the user to type y, Y, or the Enter key to start the daemon; n or N to refrain from starting the daemon; or c or C to proceed with a normal, nonconfirmed startup sequence. Again, the script that is about to run is checked for a reference to the daemon or action procedures from the /etc/init.d/functions file. If such a reference exists (or if the script about to run is halt or reboot, the scripts that alter the run level), some variables are unset (LANG, LC_ALL, TEXTDOMAIN, and TEXTDOMAINDIR) and the script will be called with start as a command-line argument. This mechanism ensures that the output on the console is consistent for all daemons that are started. When that loop completes, all daemons that should be running at that run level will have been started. The rc script then terminates. Using run level 3 as an example of a common run level to start up your system (as set by the initdefault described earlier), the rc script traverses the /etc/rc3.d directory. It first looks for any program (most likely a shell script) with a name beginning with K. It runs each of these in turn, giving it an argument of stop, with the intention of killing the named processes. It then executes all programs that begin with S, using an argument of start, to run the named processes. Note The other common start-up run level for a Linux workstation is run level 5. The main difference between 3 and 5 is that the GUI starts at level 5 while you are just in command mode at level 3. (To start the GUI while you are in run level 3, type startx.) Understanding run-level scripts A software package that has a service that needs to start at boot time (or when the system changes to any run level) can add a script to the /etc/init.d directory. That script can then be linked to an appropriate run-level directory and either be started or stopped (to start or stop the service). Table 12-6 lists many of the typical run-level scripts that are found in /etc/init.d, and explains their function. Depending on the Red Hat Linux software packages you installed on your system, you may have dozens more run-level scripts than you see here. (Later, I describe how these files are linked into particular run-level directories.) Table 12-6: Run-Level Scripts Contained in /etc/init.d Run-Level Scripts What Does It Do? apmd Controls the Advanced Power Management daemon, which monitors battery status, and which can safely suspend or shut down all or part of a machine that supports it. atd Starts or stops the at daemon to receive, queue, and run jobs submitted via the at or batch commands. (The anacron run-level script runs at and batch jobs that were not run because the computer was down.) autofs Starts and stops the automount daemon, for automatically mounting file systems (so, for example, a CD can be automatically mounted when it is inserted). crond Starts or stops the cron daemon to periodically run routine commands. dhcpd
Searching for affordable and proven webhost to host and run your servlet applications? Go to Linux Web Hosting services and you will find it.