Categorie: 02.B Linux basis – 2017 (update)

What is Unix ? The Unix operating system is a set of programs that act as a link between the computer and the user. The computer programs that allocate the system resources and coordinate all the details of the computer’s internals is called the operating system or the kernel. Users communicate with the kernel through […]

All data in Unix is organized into files. All files are organized into directories. These directories are organized into a tree-like structure called the filesystem. When you work with Unix, one way or another, you spend most of your time working with files. This tutorial will help you understand how to create and remove files, […]

A directory is a file the solo job of which is to store the file names and the related information. All the files, whether ordinary, special, or directory, are contained in directories. Unix uses a hierarchical structure for organizing files and directories. This structure is often referred to as a directory tree. The tree has […]

File ownership is an important component of Unix that provides a secure method for storing files. Every file in Unix has the following attributes − Owner permissions − The owner’s permissions determine what actions the owner of the file can perform on the file. Group permissions − The group’s permissions determine what actions a user, […]

An important Unix concept is the environment, which is defined by environment variables. Some are set by the system, others by you, yet others by the shell, or any program that loads another program. A variable is a character string to which we assign a value. The value assigned could be a number, text, filename, […]

Printing Files Before you print a file on a Unix system, you may want to reformat it to adjust the margins, highlight some words, and so on. Most files can also be printed without reformatting, but the raw printout may not be that appealing. Many versions of Unix include two powerful text formatters, nroff and […]

You can connect two commands together so that the output from one program becomes the input of the next program. Two or more commands connected in this way form a pipe. To make a pipe, put a vertical bar (|) on the command line between two commands. When a program takes its input from another […]

A file system is a logical collection of files on a partition or disk. A partition is a container for information and can span an entire hard drive if desired. Your hard drive can have various partitions which usually contain only one file system, such as one file system housing the /file system or another […]

There are 3 special permission that are available for executable files and directories. These are : 1. SUID permission 2. SGID permission 3. Sticky bit Set-user Identification (SUID) Have you ever thought, how a non-root user can change his own password when he does not have write permission to the /etc/shadow file. hmmm… interesting isn’t […]

There are three types of accounts on a Unix system − Root account This is also called superuser and would have complete and unfettered control of the system. A superuser can run any commands without any restriction. This user should be assumed as a system administrator. System accounts System accounts are those needed for the […]