Pass the LPI LPIC Level 1 101-500 Questions and answers with CertsForce

 The nice command is used to start another command with a given nice level. The nice level is a value that affects the scheduling priority of a process. A lower nice level means a higher priority, and a higher nice level means a lower priority. The default nice level is 0, and the range is from -20 to 19. Only the superusercan assign a negative nice level to a process. The nice command can also be used to display the current nice level of a process by using the -n option. References:

LPI 101-500 Exam Objectives, Topic 103.3, Weight 3

LPI Learning Materials, Chapter 3.3, Process Management

Web Search Results, 1

The correct commands to create an ext3 filesystem on /dev/sdb1 are /sbin/mke2fs -j /dev/sdb1 and /sbin/mkfs -t ext3 /dev/sdb1. These commands format the partition /dev/sdb1 with the ext3 filesystem type. The first command uses the mke2fs utility with the -j option, which enables journaling. The second command uses the mkfs utility with the -t option, which specifies the filesystem type. Both commands are equivalent and can be used interchangeably. The other options are incorrect because they use the wrong syntax or parameters for the commands. Option C is wrong because the -c option for the mkfs command checks the device for bad blocks, not the filesystem type. Option D is wrong because there is no such utility as mke3fs. The correct utility name is mke2fs.

The correct answers are C and E. Instead of supplying an explicit device in /etc/fstab for mounting, you can also use LABEL or UUID to identify the intended partition. LABEL is a human-readable name that can be assigned to a partition using tools such as e2label, tune2fs, or gparted. UUID is a universally unique identifier that is automatically generated for each partition and can be obtained using tools such as blkid or lsblk. Using LABEL or UUID instead of device names can be useful for avoiding problems caused by device name changes, such as when adding or removing disks. For example, instead of writing something like this in /etc/fstab:

/dev/sda1 /mnt/example ext4 defaults 0 0

You can write something like this:

LABEL=example /mnt/example ext4 defaults 0 0

or

UUID=80b496fa-ce2d-4dcf-9afc-bcaa731a67f1 /mnt/example ext4 defaults 0 0

The other options are not valid ways to identify a partition in /etc/fstab. FIND, ID, and NAME are not supported by the mount command or the /etc/fstab file. For more information on how to use LABEL and UUID in /etc/fstab, you can refer to the following articles:

How to Use UUID to Mount Partitions / Volumes Under Ubuntu Linux

How to Use Labels and UUIDs to Mount Partitions in Linux

How to use disk quota on Linux with examples

How to use UUIDs in fstab - LinuxConfig.org

The correct command to enable the setuid (suid) permission on the executable /bin/foo is:

B. chmod 4755 /bin/foo

The chmod command is used to change the permissions of files and directories in Linux. The chmod command can take either a symbolic or a numeric mode to specify the new permissions. The numeric mode is composed of four digits, each representing a different set of permissions: the first digit is for the special permissions, such as setuid, setgid, and sticky bit; the second digit is for the user permissions; the third digit is for the group permissions; and the fourth digit is for the others permissions. Each digit can range from 0 to 7, where 0 means no permissions, 1 means execute permission, 2 means write permission, 4 means read permission, and the sum of these values means a combination of permissions. For example, 5 means read and execute permissions, and 6 means read and write permissions.

The setuid permission is a special permission that allows an executable to run with the privileges of the owner of the file, instead of the user who launched it. The setuid permission is represented by the value 4 in the first digit of the numeric mode. For example, to enable the setuid permission on an executable file, use the following command:

chmod 4xxx file

where xxx is the combination of the user, group, and others permissions.

In this question, the executable file is /bin/foo, and the desired permissions are:

setuid permission enabled

user permissions: read, write, and execute

group permissions: read and execute

others permissions: read and execute

Therefore, the numeric mode for these permissions is 4755, where:

4 means setuid permission enabled

7 means user permissions: read, write, and execute

5 means group permissions: read and execute

5 means others permissions: read and execute

The correct command to enable the setuid permission on /bin/foo with these permissions is:

chmod 4755 /bin/foo

This command will change the permissions of /bin/foo to -rwsr-xr-x, where the s in the user section indicates the setuid permission.

The other options are not correct because:

A. chmod 1755 /bin/foo: This command will enable the sticky bit, not the setuid permission, on /bin/foo. The sticky bit is another special permission that prevents users from deleting or renaming files that they do not own in a shared directory. The sticky bit is represented by the value 1 in the first digit of the numeric mode. For example, to enable the sticky bit on a directory, use the following command:

chmod 1xxx directory

where xxx is the combination of the user, group, and others permissions.

C. chmod u-s /bin/foo: This command will disable the setuid permission, not enable it, on /bin/foo. The u-s option is a symbolic mode that means remove the setuid permission from the user permissions. For example, to disable the setuid permission on an executable file, use the following command:

chmod u-s file

D. chmod 755+s /bin/foo: This command is not valid because it mixes the numeric and the symbolic modes, which are not compatible. The 755 is a numeric mode that means user permissions: read, write, and execute; group permissions: read and execute; others permissions: read and execute. The +s is a symbolic mode that means add the setuid and setgid permissions to the user and group permissions, respectively. The chmod command does not accept both numeric and symbolic modes at the same time, and it will fail with an error message saying:

chmod: invalid mode: ‘755+s’ Try ‘chmod --help’ for more information.

References:

SetUID, SetGID, and Sticky Bits in Linux File Permissions - GeeksforGeeks

How to use special permissions: the setuid, setgid and sticky bits - Linux Tutorials - Learn Linux Configuration

chmod(1): change file mode bits - Linux man page

GRUB Legacy and GRUB 2 are different versions of the GNU GRUB boot loader, which is used to load Linux and other operating systems. One of the differences between them is the naming convention for partitions. In GRUB Legacy, partition numbers start at 0, while in GRUB 2, they start at 1. For example, the first partition of the first hard disk would be (hd0,0) in GRUB Legacy and (hd0,1) in GRUB 2. This change was made to avoid confusion with the Linux device names, which start at 1, such as /dev/sda1. Another reason for this change was to make GRUB more consistent with other operating systems, such as Windows and BSD, which also start partition numbers at 1. References:

GNU GRUB Manual 2.06: Changes from GRUB Legacy

What are the differences between GRUB and GRUB2 Boot Loader

 The signal that is sent by the kill command by default is SIGTERM(15). The kill command sends a signal to a process to terminate it. The signal can be specified by name or number as an option to the kill command. If no signal is specified, the default signal is SIGTERM(15), which means terminate. The process can catch this signal and perform any necessary cleanup before exiting. The SIGHUP(1) signal means hang up and is usually sent when the terminal or network connection is disconnected. The SIGQUIT(3) signal means quit and is usually sent when the user presses Ctrl-\ on the keyboard. The SIGKILL(9) signal means kill and is used to force the process to terminate immediately, without any chance to catch the signal or perform any cleanup. References: LPI Exam 101 Detailed Objectives, Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.3: Perform basic file management, kill command, Signal List

The file /proc/mounts contains a list of all currently mounted devices in the system. It is a pseudo-file that is dynamically generated by the kernel and reflects the actual state of the mount table. It has a similar format to /etc/fstab, but shows the actual mount options and file system types used by the kernel. The file/proc/mounts can be read by any user, but only the root user can modify it. The file /proc/mounts is also known as /proc/self/mounts, which is a symbolic link to the mounts file for the current process. References:

Understanding the /proc/mounts, /etc/mtab and /proc/partitions files

How to get the complete and exact list of mounted filesystems in Linux?

The /proc Filesystem

The command yum check-update prints a list of available package updates when using RPM-based package management. This command queries all enabled repositories and shows the packages that have updates available, along with the new version number. This command does not actually update any packages, but only lists them. To update the packages, the command yum update can be used. The other commands are either invalid or belong to a different package management system. dpkg is a low-level tool for Debian-based package management, and yum list shows all available packages in the repositories, not just the ones that have updates. References:

Linux Package Management with Yum, RPM, Apt, Dpkg, Aptitude and Zypper - Part 9

rpm - RPM package management tool | Linux Docs

RPM Command in Linux | Linuxize

 The ps command will produce the output shown in the image. The ps command displays information about the processes running on the system. The output format can be customized by using different options. For example, ps -aux will show all processes with detailed information, such as user, PID, CPU, memory, command, and so on. The output in the image matches the format of ps -aux. The jobs command will show the status of jobs in the current shell. The proclist command is not a valid Linux command. The netstat command will show network connections, routing tables, and statistics. References: LPI Exam 101 Detailed Objectives, Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.3: Perform basic file management, ps command, jobs command, netstat command

 When planning a partition scheme, it is advisable to consider creating separate partitions for some directories that may contain large amounts of data, have different backup or security requirements, or benefit from being on different filesystems. Some of the common directories that could be considered for separate partitions are:

/home: This directory contains the personal files and settings of the users. Creating a separate partition for /home can make it easier to backup, restore, or upgrade the system without affecting the user data. It can also improve security by allowing different mount options such as noexec or nosuid. Additionally, it can help to prevent the system from becoming unusable if the users fill up their disk space with personal files123.

/var: This directory contains variable data such as logs, caches, spool files, databases, and web server content. Creating a separate partition for /var can prevent the system from crashing or becoming unresponsive if the /var partition fills up due to excessive logging or caching. It can also improve performance by allowing different filesystem options such as noatime or nodiratime. Furthermore, it can enhance security by isolating the data that may be modified by external sources such as web applications or mail servers124.

/opt: This directory contains optional software packages that are not part of the standard distribution. Creating a separate partition for /opt can make it easier to manage, backup, or remove these packages without affecting the rest of the system. It can also allow different filesystem types or features that may be required by some of the software installed in /opt125.

Other directories that could be considered for separate partitions are /boot, /tmp, /usr, and /srv, depending on the system requirements and preferences12 . References:

Linux Partitioning Recommendations | Average Linux User

Linux Disk Partitioning Schemes - Land of Linux

C.3. Recommended Partitioning Scheme - Debian