With the operating system user instructions
Operating system and other programs that directly controls the hardware resources through the operating system to access the computer system's resources. Users can Interact operating system in two ways-the
1. system call
2. operating system commands
By system calls:
System calls provide the interface between the operating system and can process. It may happen that when a program is run, it says process. Calls before the system was written in assembly language, but nowadays the High-Level-Languages such as C, C ++, Pascal, etc., can also be written. System call can be grouped into five categories -(A) Process Control -
Running status of any program is called process. Execution of any running program, either generally or at the end of his Execution Execution Aboart between the halt may be the same ie.If there are no system calls a program run by Aboart in the middle of the process, ie, its execution is terminated, the operating system, memory dump and an error message is written to the disk generates. The memory dump is written to disk, the debugger monitored to ensure the problem is caused. Both normal or abnormal termination of process conditions that transfers control to the operating system command Inter printers. Inter printer command is then read the next command. Intrpritr interactive system command to read the next command is executed while the next batch jobs in the system command to terminate Intrpritr read the entire job is executed.
(B) File Management -
The system calls that come under this category. Create a file, delete, copy and view files and are used to set. To create any files during the system is required to specify the file name. To delete the file name of the file as well as their attributes also need to check. Open any files created after doing it, or rewind can be used to read or write.Lastly need to close the file. All these processes can be completed by system calls. It may be under the file name of the file attributes, file type, etc. Protection Code to come.
(C) Device Management
(D) Information Management
(C) Communications
By operating system commands:
The user, in addition to system calls to the operating system by Operating system commands can interact. Directory of MS DOS example, if you want to see the files or all directories, you can invoke the DIR command. By your operating system commands to communicate between the user and the computer system hardware. The operating system's major objective is to solve the problem of the user, so the most common problem with the system to solve Operating programs are supplied under these programs, Web browsers, text Formats, word-processors, compilers, database systems spreadsheets come etc. These programs are known as system utilities or application programs. Inter-printer command of any operating system is the most important program.
Command Inter-printer accept commands given by the user's primary task is to execute. Some of the code to execute operating system commands Command Inter-printer holds its own, while some operating system commands in the Command Inter-printer loaded into memory by searching the file system, the command is executed with the given parameter with 's. As an example of MS-DOS command Inter-printer, which is command.com, holds several commands to execute code. To delete a file by the user, such as the DEL command, command Inter-printer (command.com) is executed by the accepted. While in UNIX commands to delete the file named abc is given by the user, then his command Inter-printer, abc file named by searching the file system, load it into memory, abc is executed with the parameter. Therefore conclude that any command in UNIX's functionality is defined in a separate file, not in command Inter-printer.
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