Kernel

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....

script’s return value is stored in the environment variable represented by $?: echo $?

Explain the features and capabilities of bash shell scripting. Know the basic syntax of scripting statements. Be famailiar with various methods and constructs used. Test for properties and existence of files and other objects. Use conditional statements, such as if-then-else blocks. Perform arithmetic operations using scripting language.