Found 41 Articles for Unix

The Linux kernel modules can be loaded or removed from the kernel as required. This can be done without recompiling the kernel or rebooting the system and it enhances the functionality of the system.Without the kernel modules, the operating system would have to include all the systems that provide all anticipated functionalities in the base kernel. This would lead to wastage of memory as most of those systems would not be used often. Also, the users would need to rebuild and reboot the base kernel every time they would require a new functionality.The kernel modules have a .ko extension and ... Read More

The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers. System calls are usually made when a process in user mode requires access to a resource. Then it requests the kernel to provide the resource via a system call.A figure representing the execution of the system call is given as follows −As can be seen from this diagram, the processes execute normally in the user mode until a system call interrupts this. Then ... Read More

Solaris is a Unix based operating system that was developed by Sun Microsystems and after its acquisition by Oracle, it is known as Oracle Solaris. It is known for its scalability and its innovative features such as DTrace, ZFS, Time Slider etc. Solaris is a microkernel design and it is not possible to create a monolithic Solaris kernel.A diagram demonstrating the structure of the Solaris operating system is as follows −The different components in the Solaris operating system structure are −HardwareThis includes the physical components of the computer system such as monitor, keyboard, data storage etc.I/O BufferI/O devices are very ... Read More

The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers.Unix System CallsSystem calls in Unix are used for file system control, process control, interprocess communication etc. Access to the Unix kernel is only available through these system calls. Generally, system calls are similar to function calls, the only difference is that they remove the control from the user process.There are around 80 system calls in the Unix interface currently. Details about some of ... Read More

The GRUB (Grand Unified Bootloader) is a bootloader available from the GNU project. A bootloader is very important as it is impossible to start an operating system without it. It is the first program which starts when the program is switched on. The bootloader transfers the control to the operating system kernel. GRUB Features GRUB is the default bootloader for many of the Linux distributions. This is because it is better than many of the previous versions of the bootloaders. Some of its features are: GRUB supports LBA (Logical Block Addressing Mode) which puts the addressing conversion used ... Read More

The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers. System calls are usually made when a process in user mode requires access to a resource. Then it requests the kernel to provide the resource via a system calls.In general, system calls are required in the following situations −If a file system requires the creation or deletion of files. Reading and writing from files also require a system call.Creation and management of new ... Read More

Unix is a multiuser, multitasking operating system that was developed by Bell Laboratories in 1969. In a multiuser system, many users can use the system simultaneously. A multitasking system is capable of doing multiple jobs. Each user interacts with their own shell instance in this type of operating system and can start applications as required.An image that demonstrates the structure of the Unix operating system is −As seen in the image, the main components of the Unix operating system structure are the kernel layer, the shell layer and the application layer.Details about these are given as follows −KernelThe kernel provides ... Read More

A shell script is a list of commands in a computer program that is run by the Unix shell which is a command line interpreter. A shell script usually has comments that describe the steps. The different operations performed by shell scripts are program execution, file manipulation and text printing. A wrapper is also a kind of shell script that creates the program environment, runs the program etc.Types of ShellsThere are two major types of shells in Unix. These are:Bourne ShellThis is the default shell for version 7 Unix. The character $ is the default prompt for the bourne shell. ... Read More

The function time.time() returns the time in seconds since the epoch, i.e., the point where the time starts.For Unix, the epoch is January 1, 1970. For Windows, the epoch is January 1, 1601.time.time() is used for benchmarking on Windows. time.time() behaves the same on both UNIX and Windows but time.clock() has different meanings.On UNIX, time.clock returns the current processor time expressed in seconds, i.e., the CPU time it takes to execute the current thread so far. While on Windows, it returns the wall-clock time expressed in seconds elapsed since the first call to this function, based on the Win32 function ... Read More

You can make use of CL_ABAP_FILE_UTILITIES => CHECK_FOR_BOM to define file encoding type and use constantly of class CL_ABAP_CHAR_UTILITIES to process the files.ClassCL_ABAP_CHAR_UTILITIESShort DescriptionUtilities for Processing Characters