Scripting and Programming (Foundations) D278

Correct Answer  D. By the shell command interpreter

Explanation

 Bash scripts are executed by the shell command interpreter, such as Bash itself, which processes each command in the script line by line. The shell reads the script, interprets the commands, and executes them in sequence. The script does not need to be compiled into an executable before running.

Why other options are wrong

 A. After Linux compiles them into executable programs

 Bash scripts are not compiled into executable programs. They are interpreted directly by the shell without the need for a compilation step.

B. By executing each line in the script as a separate process

 While each command in the script may run as a separate process, the script as a whole is executed by the shell, not by running each line as a completely separate process.

C. By the GNU debugger

 The GNU debugger (GDB) is used for debugging programs, not for executing Bash scripts. Bash scripts are executed by the shell, not the debugger.

Correct Answer

A. root

Explanation

In UNIX/Linux systems, the root user has full administrative privileges, allowing them to manage system configurations, install software, modify critical system files, and perform other high-level tasks. This user has unrestricted access to the entire system.

Why other options are wrong

B. administrator

This term is typically used in the context of Windows systems. While some UNIX/Linux systems may use the term "administrator" as a synonym for the root user, the official term for the superuser in UNIX/Linux is root.

C. super user

While the term "superuser" refers to the root user, the precise name for the user with extensive system administration powers in UNIX/Linux is root. "Superuser" is a more general term used to describe the user account with administrative access.

D. power user

A "power user" is someone with advanced knowledge of the system and can perform tasks beyond the typical user level, but they do not have the full administrative privileges of the root user. Power users may have elevated privileges but cannot make system-wide changes like the root user can.

Correct Answer

B. They lead to incorrect results without any syntax errors.

Explanation

Logic errors in a shell script occur when the script runs without crashing, but it produces incorrect or unintended results. These errors do not prevent the script from running (as syntax errors do) but lead to erroneous outputs due to flaws in the logical flow or conditions in the code.

Why other options are wrong

A. They prevent the script from running entirely

This is incorrect because logic errors do not prevent the script from running. The script will execute, but the output will be wrong due to faulty logic.

C. They cause the script to execute faster than intended

This is incorrect because logic errors typically cause the script to behave incorrectly, not necessarily faster. In fact, some logic errors may even result in inefficient execution or unintended behavior.

D. They result in the script being automatically corrected by the interpreter

This is incorrect because the interpreter does not automatically fix logic errors. These errors must be manually identified and corrected by the programmer.

Correct Answer A. Process of finding and fixing bugs in code

Explanation

 Debugging refers to the process of identifying, diagnosing, and fixing errors or "bugs" in software code. These bugs can cause the program to behave incorrectly, crash, or produce unintended results. Debugging involves various techniques, such as using debugging tools, checking log files, and stepping through the code line by line to pinpoint the source of the issue.

Why other options are wrong

 B. Process of extermination insects

 This option is irrelevant and incorrect because debugging in the context of software refers to error fixing, not pest control. The word "debugging" can also be used in the context of eliminating bugs (insects), but this does not apply to programming.

C. Not being so annoying

 This option is incorrect because the term "debugging" has no relation to personal behavior or characteristics. It refers specifically to troubleshooting and correcting software code.

D. Detect and remove concealed microphones from an area

 This option is incorrect because debugging has nothing to do with detecting or removing surveillance equipment. The term "debugging" in this context is related only to software and code, not to physical security or surveillance.

Correct Answer B. Named storage space in memory used to hold data

Explanation

 A variable is a named storage location in memory that is used to store data in a program. When a program is running, the variable can hold different types of data such as integers, strings, or floating-point numbers, and its value can be changed during the program’s execution. The name of the variable is used to refer to the stored data.

Why other options are wrong

 A. Named location on disk

 This is incorrect because a variable is stored in memory, not on disk. While data can be written to disk and retrieved, variables exist in the computer’s memory during program execution, not on permanent storage like a hard drive.

C. Is a placeholder in the program

This is partially correct in that a variable can act as a placeholder for data. However, the definition of a variable goes beyond being just a placeholder; it is specifically a memory location that holds data, which can be manipulated during the program’s execution.

D. Unknown to the computer until we fill it in

This is incorrect because a variable is defined with a name in the program, and it is known to the computer. The value stored in the variable may be unknown or uninitialized at first, but the variable itself is always known to the computer once declared.

E. What we call data with changes

This is incorrect because while variables can hold data that changes during the execution of a program, the term "variable" refers to the memory location itself, not just to changing data. Data with changes is a characteristic of what a variable holds, but it is not the definition of a variable itself.

Correct Answer

A. An iterable collection should provide a method that creates a new iterator instance.

D. An iterator generally assumes that the underlying collection is not altered while being traversed.

Explanation

 In the iterator design pattern, an iterable collection provides a method (commonly iterator() or similar) that returns a new iterator instance. This allows external code to traverse the collection without exposing its internal structure. Iterators typically assume that the underlying collection will not change during iteration to avoid unexpected behavior. This immutability assumption helps preserve consistency and prevent errors such as ConcurrentModificationException in languages like Java.

Why other options are wrong

 B. The state of an iteration is encapsulated within the iterable collection

This is incorrect because the state of iteration is usually encapsulated within the iterator object, not the iterable collection. Each iterator maintains its own state (like a current position), independent of the collection itself.

C. If two iterators are created for the same iterable collection, advancing one will advance the other

This is false. Each iterator maintains its own independent state. Advancing one iterator has no effect on the state or progress of another iterator.

E. A single iterator can be used to traverse more than one collection

 This is generally not true. Iterators are tightly coupled with a specific collection and are designed to work with the structure and elements of that particular collection. A new iterator should be created for each collection.

Correct Answer

A. read, write, execute

Explanation

In Linux, files have three primary types of permissions:

Read (r): Allows the file to be opened and read.

Write (w): Allows modifications to the file, such as editing its content.

Execute (x): Allows the file to be run as a program or script.

These permissions can be granted to the owner, the group, and others.

Why other options are wrong

B. read, write, erase

This is incorrect because "erase" is not a standard permission in Linux. The correct permissions are "read," "write," and "execute." Deleting a file is done through specific commands like rm, not by a separate permission.

C. browse, read, delete

This is incorrect because "browse" and "delete" are not standard file permissions in Linux. The correct permissions are "read," "write," and "execute." Deleting a file requires write permissions and using specific commands.

D. read, copy, delete

This is incorrect because "copy" and "delete" are not standard file permissions in Linux. The standard permissions are "read," "write," and "execute," and copying or deleting a file is controlled by these permissions but isn't directly a permission itself.

Correct Answer

C. They enhance the control over text display on the screen

Explanation

Cursor positioning commands in shell scripts are primarily used to manipulate the cursor’s position on the screen, allowing for more dynamic and visually controlled output. This is beneficial for creating cleaner, user-friendly interfaces, such as updating specific lines or clearing areas of the screen without affecting other parts.

Why other options are wrong

A. They enable the execution of multiple scripts simultaneously

This is incorrect because cursor positioning commands do not affect the execution of scripts. Running multiple scripts concurrently would require background processes or specific concurrency commands, not cursor manipulation.

B. They allow for the customization of file permissions

This is incorrect because file permission customization is done using commands like chmod and chown, not cursor positioning commands. Cursor commands are focused on display control, not file management.

D. They provide debugging information during script execution

This is incorrect because cursor positioning commands are not intended for debugging purposes. Debugging information is usually displayed using logging or error handling techniques, while cursor commands are used to control the visual layout of the terminal output.

Correct Answer

C. Menu

Explanation

A menu is a user interface element that displays a list of options. When a user selects an option, the corresponding command or action is invoked. Menus are common in graphical user interfaces (GUIs) as well as in text-based applications to allow users to easily choose from available commands or actions.

Why other options are wrong

A. Form

This is incorrect because a form is a collection of fields where users can enter data. While forms may include menus as part of the interface, the form itself is not a list of options where commands are executed upon selection.

B. Button

This is incorrect because a button typically initiates an action when clicked, but it does not provide a list of options. A button triggers a single command or action, not a menu of choices.

D. List

This is incorrect because a list is simply an arrangement of items or data. While a list may contain options, it doesn't inherently imply that selecting an item will trigger a command, as menus do.