Linux

User Accounts Linux kernel authenticated users to access files and applications. while each user is identified by a unique integer (the user id or UID), a separate database associates a username with each UID. Types of Accounts By default, Linux distinguishes between several account types in order to isolate processes and workloads. Linux has fourtypes of accounts: root System Normal Network For a safe working env, it is advised to grant minimum privileges possible and necessary to accounts, and remove inactive accounts....

Working with PostScript and PDF PostScript is a standard page description language. it effectively manages scalilng of fonts and vector graphics to provide quality printouts. The format itself is a language that Adobe developed in the early 1980s to enable the transfer of data to printers. Feature of PostScript are: it can be used on any printer that is PostScript-compatible, i.e., any modern printer. Any program that understands the PostScript specification can print to it....

Printing on Linux printing itself requires software that converts information from application you are using to a language your printer can understand. The Linux standard for printing software is the Common UNIX Printing System (CUPS) Modern Linux desktop systems make installing and administering printers simple and intuitive. Nevertheless, it is instructive to understand the underpinnings of how it is done in Linux. CUPS Overview CUPS interprets page descriptions produced by your application (put a paragraph here, draw a line there, and so forth) and then sends the information to the printer....

$RANDOM: environment variable for performing security-related tasks Reinitializing storage devices Erasing and/or obscuring existing data Generating meaningless data to be used for tests How the Kernel Generates Random Numbers Some servers have hardware random number generators that take as input different types of noise signals, such as thermal noise and photoelectric effect. A transducer converts this noise into an electric signal, which is again converted into a digital number by an A-D converter....

Basic Syntax and Special Characters Character Description # comment, shebang, # \ nextline, escapecode ; used to interpret what follows as a new command to be executed $ environment variable > redirect output » Append output < Redirect input | pipe the result into next command Putting Multiple Commands on a Single Line # run consequent command whether or not preceding one succeeded. $ make ; make install ; make clean # proceed next command only when preceding one succeeded....