Table of Contents
The computer control system consists of one or more personal computers. Each computer runs a copy of the Linux operating system. Linux is a UNIX style operating system that runs on x86 class machines.
If there is more than one computer in the system, they are interconnected by a network. One computer contains the control system software and user files. The rest of the computers access that computer through the network by using NFS. Throughout the rest of the manual, the computer containing the control system software and the user files will be refered to as the file server.
The network may also have terminal servers connected to it. Terminal servers are boxes that have a number of serial ports and a network connection. They allow incoming and outgoing connections to be made between the devices attached to serial ports and the network.
Starting the control system requires that the file server be started first, followed by the rest of the computers and the terminal servers. After all of the computers and terminal servers are up and operating, the accelerator control system may be started.
The accelerator control system is composed of a database manager program and groups of programs that communicate between the database manager and the hardware.
Linux, as well as most other large powerful operating systems, requires an organized startup and shutdown.
When the system is started, various housekeeping programs are loaded and executed. The file system is checked to insure it wasn't damaged when the system was previously turned off. These and other functions are performed in the startup process.
Shutdown is the opposite of startup. Disk buffers that are currently in memory are written back to the disk drive. Housekeeping programs are terminated and the information that has been collected is properly stored. These and other functions are done by the shutdown process.
AccelNET provides three default users. Each user serves a specific function.
Administrative/maintanence account. Used for modifications to the AccelNET database.
Administrative/maintanence account. Used for starting/stopping the AccelNET services.
General user account. Used for operating a running accelerator.
This procedure explains what to do to start an individual computer. If the system is operating correctly, things should pretty much happen as described. If there are problems, refer to the Linux manuals for more information.
Note that the file server computer should be the first machine started. Remember that the other computers use the file server.
Procedure 1.1. Linux Startup
Turn on the power.
Wait for the disk drive to reach its operating speed and for the machine to perform its power on self tests.
Wait for the booting menu to appear.
Press <Enter> (if you wait long enough the machine will proceed on its own)
Linux may decide to check the file system if it detects the computer was not shut down properly. If error messages appear while the file system is being checked, it indicates that there is a problem with the files contained on the disk. Usually it is safe to answer "y" to the questions fsck (the file system check program) asks. Sometimes the file system check will require a reboot of the machine.
When this sort of a problem occurs, it usually means that the computer was shut off or restarted in a disorganized manner. Perhaps the computer crashed, the power failed, or someone pushed the reset button. Consult the Linux manuals for more detailed information.
When the login prompt appears, the system is ready for operation.
The login name "csoperator" is provided as a default login for accelerator users. It is possible to customize the system to provide an individual login for each user. Please consult the Linux documentation for information on creating user accounts.
When the computer is powered up, it will go through a normal boot process containing messages that are usually followed by [OK]. Once the boot messages are complete, X (the graphical interface) will start up and prompt for a login.
Type in the username and password in the appropriate text boxes. The password field may not be shown on the initial screen, you will be prompted for it later if this is the case. During this time, you also have the ability to select a Window Manager. It is recommended that KDE or Gnome be used. These two selections provide the most user-friendly experience, being similar to Microsoft Windows.
This procedure explains what to do to stop an individual computer. If the system is operating correctly, things should pretty much happen as described. If there are problems, refer to the Linux manuals for more information.
Many Linux desktops have a method to shutting down using the graphical interface. Because the graphical method may vary, the command line method is described here.
Note that the file server computer should be the last machine stopped. Remember that the other computers use the file server.
Procedure 1.2. Linux Shutdown
Open a terminal (command prompt).
Super-user to root: su -
Enter the root password.
Enter the shutdown command: shutdown -h now
The system will perform a number of operations. If the system does not automatically power down, a message is displayed saying that it is safe to shut off the power.
There are other ways of shutting down, this is just one example. For example, an alternative to the above command might be poweroff.
In order to effectively to use the more advanced features of the accelerator control system, the user should be familiar with the process of logging into the system as well as the commands provided by the Linux operating system.
The concepts of pathnames, current directory, and i/o redirection are very important to a good understanding of how the Linux environment works.
Look in the Linux manual pages for descriptions of how these and other commands work.
This is a list of basic commands:
Copy and concatenate files. Used most often to print the contents of a file on the screen. Example: "cat <filename>"
Change directories. Example: "cd <new directory>"
Copy a file. Example: "cp <source> <target>"
List the contents of a directory. Example: "ls -l"
Print files. Example: "lpr <file>"
Make a new directory. Example: "mkdir <directory name>"
List the current working directory. Example: "pwd"
Remove a file. Example: "rm <file>"
This is a list of more advanced and administrative commands:
File archiving program. (used to copy to and from tape)
File system check (used when Linux is started).
Create a Linux file system.
Mount a disk partition, cd, floppy disk, etc. to be accessed as a Linux file system.
List the environment variables (see the sh manual pages).
The shell.
Unmount a file system.
Text editor.