Linux Commands Multiple Choice 2

The command "init 5" is used to initiate a change to runlevel 5. This command is commonly used in Unix-like operating systems to switch to a multi-user graphical mode. The alternative command "telinit 5" can also be used, as it is a symbolic link to the same file as "init 5". Both commands will achieve the same result of transitioning to runlevel 5.

The basic command used to create hard disk partitions is fdisk. Fdisk is a command-line utility that allows users to create, delete, and manipulate disk partitions on a hard disk. It is commonly used in Linux and Unix systems to manage the partitioning of hard drives. With fdisk, users can create new partitions, specify their size and location, and set the partition type. It is a powerful tool for managing the storage space on a hard disk and organizing data effectively.

The command "ln -s" creates a symbolic link in a Linux filesystem. This command is used to create a shortcut or reference to a file or directory. The "-s" option specifies that the link being created is a symbolic link.

The correct answer is "cmd1 | cmd2" because the pipe symbol "|" is used to redirect the standard output of cmd1 to the standard input of cmd2. This allows the output of cmd1 to be used as the input for cmd2, enabling the two commands to be connected in a pipeline.

The two interrupts usually associated with a PC's onboard serial interface are interrupt 3 and interrupt 4. These interrupts are used to handle the communication between the serial port and the computer's CPU. Interrupt 3 is typically used for the first serial port (COM1), while interrupt 4 is used for the second serial port (COM2). These interrupts allow the CPU to be notified when data is received or when the serial port is ready to send data, enabling efficient and reliable serial communication.

SUID (Set User ID) is an ext2 filesystem attribute that allows a process to take on the ownership of the executable file's owner. When SUID is set on an executable file, the process that runs the file will have the same privileges as the owner of the file, regardless of the user who executed the file. This attribute is commonly used for programs that require elevated privileges to perform certain tasks, allowing regular users to execute them without compromising system security.

The command "nice" is appended to the beginning of a command line in order to modify the execution priority of the resulting process. By using the "nice" command, the user can adjust the priority level of a process, giving it a higher or lower priority compared to other processes running on the system. This allows the user to control the allocation of system resources and prioritize certain tasks over others.

b. Both ps and top yield process status. None of the other listed commands are related to processes.

a. kill -9 is drastic but necessary for processes unable to respond to other signals.

b. The > character opens and writes to a new file, while >> appends to an existing file, unless that file doesn't exist, in which case it is opened first.

A reasonable size for a swap partition for a Linux workstation with 128 MB RAM would be 100 MB. The swap partition is used as virtual memory when the physical RAM is full, allowing the system to continue running smoothly. The size of the swap partition should generally be equal to or slightly larger than the amount of RAM in the system. In this case, 100 MB is a reasonable size considering the 128 MB RAM.

a. cat concatenates files, and as a subset, will list one or more files to standard output. tac lists files in reverse order.

e. A filesystem without free inodes cannot create new objects until existing objects are removed.

a. User mode 7 is the same as u=rwx, group mode 5 is the same as g=rx, and other mode 4 is the same as o=r. The ~/ syntax implies the user's home directory.

e. Using the & character puts a program in the background.

d. The -p, or preserve, option is required to retain dates.

d. The tr program translates characters from one group into another, including case.

c. Provided that file is an RPM file, the -U indicates that an upgrade should occur. -h turns on hash marks.

c. tar should be used with the extraction option x and a tape device, such as SCSI tape /dev/st0.

c. The sticky bit in the mode prevents deletion by non-owners, but root can still delete the file.

c. CD-ROMs use the iso9660 filesystem, which is the default for mount, but also indicated using -t. Without the assistance of an entry in /etc/fstab, both the mount device (/dev/cdrom) and the mount point (/mnt/cdrom) must be provided.

d. Linux has no control over the BIOS settings.

d. The tail command is used for checking the last lines of a text file. By default, it displays 10 lines.

b. init, the grandfather of all processes, always has PID 1.

d. The shadow password system has been implemented, placing all passwords in /etc/shadow as denoted by the x following the username.

c. df reports disk information, including a percentage of the filesystems used. Answer a is incorrect because /home may not be the only partition on the physical disk.

e. :bye is not a valid command in vi.

b. A metacharacter is a special character that is used to modify and control the interpretation of literals. File globbing is generally considered distinct but very similar to the use of regular expressions.

d. The [Ll] matches both letters.

d. PCs usually have two IDE interfaces, each capable of handling two devices.

b. The query mode is required, which implies -q. The -a option in query mode yields all packages.

e. IDE disk drives are referred to as /dev/hdx, where x is a, b, c, or d. Partitions are numbered from 1 through 4 for primary and extended partitions and 5 through 16 for logical partitions.

d. The nl command numbers lines.

a. The variable must be set and exported. The semicolon separates the two commands.

c. The g indicates that we're operating on the group privilege, and the +s indicates that we should add the "set id" bit, which means that the SGID property will be applied.

d. Xsession is the system-wide default application startup file.

a. ld.so.conf is the text file in which you add library directories. ld.so.cache is the binary index resulting from ldconfig.

c. While answers b and d are technically correct, answer c best describes /sbin.

e. Ctrl-Z stops the job and gives control back to the terminal. bg places the job into the background and restarts it.

c. This is an example line from the output of df -h, the "human-readable" mode of df.

a. The appropriate option is either -s or --status.

b. By default, files do not have the execute privilege, which rules out all responses containing odd numbers in the mode. They also do not by default have the sticky bit set, which eliminates response e. Response b is the result of masking initial bits 666 with umask 027, leaving 640, which is the same as 0640.

b. The write will continue until the hard limit of 110 MB is reached, after which the write fails and data is lost.

e. /var and /tmp are mainly transient, /usr is typically static (and should be easy to reinstall from the original OS media), /root is simply a home directory for root, but /etc contains system configuration information that frequently changes.

An administrator might use the --force option for rpm to forcefully delete installed packages. This option allows the administrator to bypass any warnings or confirmation messages that would normally be displayed when attempting to delete a package. By using this option, the administrator can ensure that the package is deleted without any interruptions or prompts.

c. The octal dump program, when used with the -t x option, will output in hexadecimal notation.

The correct answer is /proc/ioports. The /proc/ioports file contains information on the I/O port assignments in use. This file is a virtual file system that provides an interface to kernel data structures, allowing users to access information about various system resources. In the case of I/O port assignments, this file specifically lists the ranges of I/O ports that are currently in use by devices on the system.

d. The first echo argument is unquoted and thus returns its contents, ls. The second is quoted with double quotes, which do not preserve the $, so it too returns ls. The third is quoted with single quotes, which do preserve the $, so it returns the string $MYVAR. The last argument is backquoted, which means that it returns the result of the command stored in $MYVAR. The command is ls, which displays the only file in the directory, Afile1.

d. Brackets ([ ]) are used to group a character set consisting of numbers 18 and characters A-Z and a-z. The ^ just inside the opening bracket negates the whole string, such that the string matches numbers 0, 9, and symbols.

a. The !! command history expansion executes the previous command. Entering the Ctrl-P keystroke uses the Emacs key-binding bash to move up one line in the history; pressing Enter executes that command.